Eduart Zimer - (SDU) - Adventive Plants - Part 9 (2010)

7/23/2019 Eduart Zimer - (SDU) - Adventive Plants - Part 9 (2010)

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Succulent plants from down under – Adventive Plants (Part 9):

Crassula coccinea – Intermezzo: a new erratum – Aloe arborescens – Notes on Aeonium

‘Rangitoto’ (II)

XXI. Crassula coccinea

Crassula coccinea Linnaeus 1753 - synonyms are Rochea coccinea (Linnaeus) De Candolle and Rochea odoratissima (Andrew) Link - used to be one of the glories of the New Zealand cottagegardens only until few decades back; it has gone out of fashion since and today even in Auckland’sold residential area gardens there are slim chances to see one. But there is still a place where itthrives in the wild – Rangitoto Island. I wrote few words about this plant in Part 7 of this series, but Ithink it is time for more details on the naturalization of this amazing plant.

Crassula coccinea is an erect and almost glabrous sub-shrub to 50 cm high, with initially succulent

stems up to 13 mm thick, becoming woody with age. The leaves are succulent, sessile and in fourranks, strongly imbricate and scarcely aggregated toward the apex of the stems, 20 – 30 x 13 – 17mm, elliptic or ovate-oblong, almost flat, green coloured, without hydathodes and with obtuse apex.The thyrse is to 8 cm across; the flowers are 5-merous to 20 – 24 mm diameter and up to 25 in athyrse. The lobes are lanceolate with ciliolate margins; corolla is 40 – 47 mm long and not star-likeshaped, tube is 30 – 35 mm long whitish at the base and pink above, the 5 lobes are 10 – 12 mmlong, ovate-oblong to elliptic-oblong, crimson and becoming recurved. Seeds have not been observedin New Zealand plants.

As most of the Crassula species it originates from South Africa, Western Cape. Although it prefersthe proximity of coastal areas it is not an actual sea shore plant as it grows high in the mountains,

1. A young Crassula coccineastem emerging from an almost

dead plant. This vegetative

“regeneration” is probably

the most common self-

propagation on Rangitoto. The photo was taken at Yankee

Wharf.

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usually at about 800 m altitude and above. A reference location for Crassula coccinea is TableMountain, where it grows together with other bright red flowering plants like Disa uniflora, Disa

ferruginea, Nerine sarniensis or Tritoniopsis triticea, all being pollinated by the same endemic

butterfly - Meneris tulbaghia, which shows a peculiar preference for red flowering plants (Ernst vanJaarsveld & Liesl van der Walt, 2001).

2. The wonderful thyrse of

Crassula coccinea. The

bright red colour is hard tocapture on camera. The photo

was taken at Yankee Wharf

(Rangitoto).

3. Crassula coccinea and

Crassula multicava plantlets

near an old cultivation site

close to Rangitoto wharf in the

southern part of the island.




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In its natural habitat Crassula coccinea prefers steep slopes of quartzitic sandstone or bare rockswhere it forms small succulent subshrubs, more or less branching from the base (1). The plant itself issomewhat non-descriptive, with dull stems turning woody and brown as they grow (2) and retaining

the shriveled rests of the dead leaves, very persistent and untidy looking, and with the new imbricategreen leaves at the end of the stems. But what a show in mid-summer when it gets to flower! Firstthing you notice is the colour (very striking especially in full sun) – a bright red of a kind you havenever seen before! The tubular flowers are quite big for a Crassula and slightly fragrant as well sothat they deliver an incredible package for such a dull plant. The bright red colour is however not theresult of pigmentation but of a peculiar cellular structure - Rudolph Marloth (in Flora of SouthAfrica, 1913 – 1932): "This dazzling brightness of the flower is principally due to the dome-shaped

form of the epidermal cells, each acting like a combination of a convex lens with a concave

reflector" .

Crassula coccinea has been first collected in Rangitoto Island by W.R. Sykes in September 1982 andsubsequently published by C. J. Webb, W. R. Sykes & P. J. Garnock-Jones in Flora of New Zealand,Vol. 4, 1988 and by D.R. Given in his 1984 Checklist of naturalized plants. It has been also recordedin Canterbury since (D.J. Mahon, 2007).

4. Cultivated plant in my rock garden.




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In Rangitoto Crassula coccinea is a typical garden escape, mostly very persistent in or around theabandoned gardens of the former baches (still thriving in some places) but is has also migrated on

grounds altered by human activities (i.e. at Yankee Wharf, where roads building and quarrying havescattered finer particles in the area favouring the development of different vegetation patterns)sometimes few hundred meters from the original locations. It is very common on the north-eastern(Gardiners Gap, Islington Bay) and eastern (Yankee Wharf) coasts of Rangitoto, also very commonin few spots along the southern stretch of the Islington Bay Road, not too far from the RangitotoWharf, but it doesn’t form anywhere strong populations. However, you can’t miss it in high summer– you’ll see the bright red inflorescences from the distance, scattered on the black lava blocks.

In most of the locations where I have seen it here the soil is virtually absent, and the plants have totake full advantage of every fissure or small crevice of the basaltic lava blocks. It may be a similartype of substrate but as a whole, its original habitat is rather different I think. At least at 800 maltitude it is lacking in marine exposure. For a change – in Rangitoto it faces the sea. At IslingtonBay and at Yankee Wharf the plants come quite close to the waterline and even if the shallow waters

of the narrow channel between Motutapu and Rangitoto islands do not become exactly a raging seaeven on stormy weather, salt laden mist is quite common. In the southern parts few miles of open seaallows probably for even higher exposure especially when strong southerlies batter the shores.However, as many other South African succulent plants originating from coastal areas or fynbos,Crassula coccinea has managed to adapt perfectly here. I have no idea about the whereabouts of thisplant in Canterbury, but I can only assume that here as well there are good chances of following thesame distribution patterns as most of the similar plants – the coastal areas. However, a commonfeature with its original habitat is the mild and humid winter, very important as it is a winter grower.

Although well settled in several corners of the island there are not too many plants, at least I haven’tseen more than casual scattered plants here and there. It seems that there was no seed dispersal here;

5. Cultivated plant in my rock

garden showing a sudden

variegation. It must have been a

viral condition as this variegation

has appeared at two neighboring plants, never to appear next year.




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at least the low number of young plants suggests this. More, in several instances the young plantswere emerging from remainders of old or apparently dead plants which indicate rather the vegetativedispersal, and rather localized I would say. However, for any dispersal – and in some corners like

Yankee Wharf there’s quite a stretch to the nearest bach - there must be a vector, but unfortunately Idon’t have a clear explanation in this case.

It is true that Crassula coccinea is a typical garden relict; it is also true that in most of the cases theplants grew within the boundaries of former properties or gardens; it is also very well known howpersistent and self-maintaining patches of old vegetation can be. But there is no satisfactoryexplanation – in the absence of seed – of how this plant could travel few hundred meters from itsoriginal location in Islington Bay to the succulent corner south of Yankee Wharf. There are no easilydetachable parts (branches, leaves) which could be for example easily blown by wind; I can acceptthis explanation for the tiny plantlets spread by Crassula multicava or for the small succulent leavesof Crassula tetragona ssp. robusta (3) but not for the strong branches of Crassula coccinea, heavyenough not to be blown away on long distances very easily.

6. A small group of Crassula coccinea established quite off the old cultivation site close to Rangitoto

wharf in the southern part of the island. Of course Crassula multicava plantlets are also present.




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It also appears that the growth rate of the Rangitoto naturalized plants is much reduced compared tocultivated plants. It is said that it can flower in one year even from seed, if cuttings are taken it neverfails to flower the following summer, at least for me. Observing the small plants, the side offsets,

etc., my feeling is that it can take 2 or even 3 years until they get to flower. But this would makesense in such a hostile environment.

However, it is a very nice addition to the adventive succulent flora of Rangitoto Island, not tooinvasive and easy to control, which is very important for conservation matters in such iconic naturallandmarks.

XXII. Intermezzo: a new erratum

There is something I have learned over the last few years since I have jumped into succulent plants

naturalization in New Zealand – it takes sometimes a lot of time to understand things and how theywork, to get around with all the literature and accounts published over the years or simply youdevelop in time different views. Fact is that there were (and still are) few white spots on the map forme and I might have even stabbed in the dark few times. Therefore I have decided now (April 2010)to fix some other blurts from the past. And here we go again:

a) The true number of naturalized plants.

In the opening chapter of Part 1 I wrote:

A number of 615 alien plants were recorded from 1840 until 1985 (Esler &Astridge, 1987) and even though some of the recorded species were just

casuals or occurring just rarely and were not found again in later

assessments, the actual number of the adventive plants recorded until now

must be well over 700.

And further down in my note no. 2:

Esler & Astridge (1987) are considering that the naturalization rate of one

new species at 88 days (or 4.12 species per year) was maintained over the

years; if so, this will add about 90 new species between 1985 and 2007. In

my opinion, as the greatest pressure in our days comes from horticulture

(at no time in New Zealand’s history the number of species and hybrids on

offer at Garden Centers was greater, at no time there was such aresidential boom), it is quite possible that we have passed by now the 750

or even 800 mark. Other sources are mentioning 2,200 – 2,500 adventive

species (this would mean half of the total plant species growing in New

Zealand) but (…) I think the numbers are highly overrated and/or may

include all sorts of casuals with no chance of long-term survival.

I have done two major mistakes here. First of all Esler & Astridge (1987) wrote in their paper aboutGreater Auckland and not New Zealand, which I have failed to observe at that time in my notes(bugger!) compiled from various sources, including this account. I wasn’t excelling in good qualityresearch I guess, that’s a thing that I have learned in time. However, I wrote this probably in October




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2007 (when I started this series) being concerned about the true meaning of the word naturalization only later in January or February 2008 while working on Part 2 (and this was my second mistake).As I already stated before – I was on a steep learning curve and apparently things weren’t too clear

for me at that time.

My point is that adventive plants do not consist only of naturalized and casual as defined in Part 2but I would rather extract the persistent cultivation relics and the spontaneous occurrences from thelater as self-standing categories. There is no doubt that some of the advanced figures of up to 2,500plants refer not only to naturalized plants but includes the casual, spontaneous occurrences and persistent cultivation relics as well and are possibly over-rated as spontaneous growth may occur,may be recorded only to disappear for good in that particular area. At this point in time I will notadvance any numbers, but definitely will look into this.

b) The Sedum praealtum ssp. praealtum distribution.

In Part 2 (chapter IV – The Sedum group) I wrote:

[Sedum praealtum ssp. praealtum] is an alpine plant though, reportedly

occurring just in the southern third of the North Island and all over the

Southern Island and even enjoying the sub-polar influences of the far

south.

This was October – November 2007. At that time I was relying mainly on the 1984 David R. GivenChecklist (which indicated in the North Island just Palmerston North, Bunnythorpe and Wellington)and haven’t seen this plant in Rangitoto yet. On the other hand a quite rare article (not available onthe internet), namely W.R. Sykes’ 1992 Succulent Plants on Rangitoto Island (published inAuckland Botanical Society Journal), wasn’t consulted yet at that time. Truth is that Sedum

praealtum ssp. praealtum does very well in the cooler South Island, but it also managed to establishin Rangitoto, which is quite remarkable in fact. Also, it happened that I first saw Sedum praealtum ssp. praealtum in Rangitoto only in January 2008.

c) The presence of Aeonium arboreum on Rangitoto.

In Part 4, chapter X. A brief overview of the adventive succulent flora of Rangitoto Island I wrote:

I will start with a plant having an uncertain status – Aeonium arboreum

[Webb & Berthelot [Morocco]; it is unknown if this plant has been actually

seen on Rangitoto or anywhere else in New Zealand although there are a few

references. Apparently it was Healy’s confusion in 1959 (reportedly he

confused Aeonium cf. ciliatum for Aeonium arboreum), many have referred him

later, but when his error has been discovered years later all authors tend

now to link any reference of Aeonium arboreum to this error, which might

be of course not true. However, little is actually known other than this

plant is a doubtful occurrence.

Again W.R. Sykes’ Succulent Plants on Rangitoto Island has provided me with very goodinformation, unfortunately too late. “The Rangitoto record of A. arboreum (L.) Webb et Berth. in




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Webb et al. (1988) (4) is erroneous, being based on a specimen of A. undulatum (Gardner S249,

Islington, 18 Jul. 1987, AK).” I don’t know if C.J. Webb has been tricked in by A.J. Healy’s 1959misidentification, however, he was wrong about the presence of Aeonium arboreum on Rangitoto.

More, W.R. Sykes himself was co-author of Flora of New Zealand Vol 4. (1988) – freely availablenowadays as internet resource - but didn’t clarify the matter until his 1992 account.

d) Omitted Rangitoto adventive succulent plants.

On several occasions I have complained about the lack of information in relevant botanical literature(such as the many Checklists for naturalized plants) considering that only by going out in the fieldand browsing areas of interest you can get a true picture. On several occasions – and my referencesregarding Aloe arborescens and Aeonium haworthii on Rangitoto are possibly the best examples -botanists have failed to observe some species in natural environments. In some instances I still think

I was right, in some other… well, it is obvious that botanists have had their omissions and so had I.Fact is that most botanical accounts (such as the references in the Checklists of naturalized plants)are based on herbarium collections. Even if you consult the electronic version of Flora of NewZealand and want to check the dispersal of a certain species you will have a short general descriptionof the distribution area with few relevant localities and possibly a map showing the locationsherbarium collections were made from; in some instances there is not a perfect match between thetwo, in some other instances it is even very clear that there is definitely a lack of information – andthe best example would be the Cotyledon orbiculata seen by me in two sub-populations in Piha. IfAnawhata is mentioned, I would also expect the more iconic Piha to be referred as well for thismatter. Not to speak of Rangitoto where applicable.

However, in some of the cases the information was there (even if not properly acknowledged in thebotanical literature) – I have recently managed to get a copy of a very interesting article, referred bysome authors, but which had never the circulation it should have deserved: W.R. Sykes - Succulent

Plants on Rangitoto Island (published in Auckland Botanical Society Journal in 1992). I have onlyrecently found this article in the Alfriston Botanic Gardens library. Ironically, I am a constant visitorof the gardens and I pop in every now and then in the library to make some research if otherresources (especially internet, my personal electronic library or the few books I have) fail to providethe needed information, but sadly I have missed this article for a very long time…

Ironically – W.R. Sykes shares the same concern: naturalized plants are only superficially studied,even in unique and therefore highly important habitats such as Rangitoto. “ However, in and around

these settlements the resulting community is especially rich in Crassulaceae and, although most ofthem also occur elsewhere in New Zealand, the combination of species and the frequency of some of

them is unique to Rangitoto. This uniqueness is a reflection of the combination of climate and the

unusual geological structure of the island. Little attention has been paid to them botanically

however, although many records are scattered through the pages of Webb, Sykes & Garnock-Jones

(1988). The aim of this account is to remedy this defect.”

Long story short – this article brings some additions to my list of adventive succulents on Rangitoto(Part 4, chapter X.), mainly a handful of omitted true succulent species, but also several speciesdisplaying a marginal succulent habit I would have never considered at that time (5). And here wego:




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- Agavaceae:

• Agave americana Linnaeus 1753 ‘Variegata’, the variegated form originating from Mexicoand USA – of which W.R. Sykes maintains to have seen it growing next to uniformly green-leaved plants, which is a real surprise for me. I haven’t seen any and I highly doubt that thereare anymore variegated plants growing on the island. We know that nowadays the Agave colony is periodically checked which wasn’t the case back in the late ‘80s and early ‘90s as“although not seen in flower, the old dead inflorescences were 4 – 5 metres high ”. I put someeffort in studying the Islington Bay colony and I can certify that there were no variegatedplants there. I also haven’t seen any plants (variegated or not) near Rangitoto wharf which isindicated as a second locality or near Wilson’s Park at the crater rim – a real surprisinglylocation. Being massive plants I think that it was merely possible to stay under the radar ofthe environmental bodies, especially if some quick and highly visible impact of the

vegetation control program is wanted. I would rather suggest that due to intense vegetationcontrol over the last few years the variegated form has been eradicated.

• Yucca recurvifolia Salisbury 1807 (also referred as Yucca gloriosa var. recurvifolia (Salisbury) Engelmann 1873) is indigenous to coastal areas of the south-eastern USA andwas mentioned as “occasional growing as relics of cultivation on old garden sites” nearIslington and Rangitoto wharf.

- Aizoaceae:

• Lampranthus sp. (not fully indentified) indigenous to South Africa, unfortunately no locationis given.

- Asphodelaceae:

• Aloe arborescens (Linnaeus) Miller 1768 is indigenous to southern regions of Africa. Ibecame aware of the presence of this plant here (it was quite a surprise actually!) well after Iwrote Part 4, so that it belongs to this list. W.R. Sykes indicates Islington, Rangitoto wharfand surprisingly Wilson’s Park “at base of crater one”. The plants I have seen were locatednear Yankee Wharf which is south of Islington Bay wharf, well away from former bach sites.I still don’t know how the plants got there and it somewhat contradicts W.R. Sykes whomaintains that “the plants are thriving and flowering freely but cannot be considered

adventive because they have not reproduced themselves” because of the remote location. It isstill a mystery to me how Aloe arborescens got there.

• Aloe ciliaris Haworth 1825 is another South African native which surprisingly pops up inIslington. “One straggling plant on an old garden site” notes W.R. Sykes (I wonder ifstruggling wouldn’t have been a more adequate word to use). Collected by W.R. Sykes inDecember 1989 is possibly gone extinct by now.




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- Asteraceae:

• Senecio angulatus Linnaeus f. 1782 is a South African native plant with sub-succulent leaveswhich forms a few patches around old house sites in Islington. “ It may not form viable seed

as no seedlings or young plants were seen”. However, it is considered a problem weed inNew Zealand – it is also blacklisted by Wotherspoon & Wotherspoon (2003), which I failedto observe.

- Araceae:

• Alocasia brisbanensis (Bailey) Domin 1915 from Australia is recorded by W.R. Sykes inWilsons Park, at the base of the crater cone, just few plants. I vaguely remember seeing thisplant (but without being able to locate exactly where on the island); however, unfortunately Ididn’t take any picture of his rather non-interesting (for me at least) sub-succulent plant witha rather nice vernacular name – Elephant’s Ear. During my only foray to date throughWilsons Park I was quite on a tight schedule and – honestly – it also didn’t match myexpectations for the site of an intended botanic garden. W.R. Sykes also notes that thisspecies has been also confused in New Zealand botanical areas with Alocasia macrorrhizos, aPolynesian species.

• Colocasia esculenta (Linnaeus) Schott 1832 is indigenous to the Indo-Malaysian region.W.R. Sykes mentions again few patches growing in Wilsons Park. I don’t know the plant andthere’s no wonder if I would have considered it to be native.

• Zantedeschia aethiopica (Linnaeus) Sprengel 1826 is a South African plant I wouldn’t evenconsider a typical succulent. However, W.R. Sykes mentions two locations – the WesternEnd (McKenzie Bay) and again Wilsons Park “at the base of crater cone” “a large stand

densely covering many square meters of the rough lava surface beneath pohutukawa hybrids”( Metrosideros excelsa x Metrosideros robusta). I know very well this plant (how couldn’t Ias in most of Auckland’s old fashioned cottage gardens is still placed in privileged spots) buthave to admit that I haven’t noticed its presence. Being blacklisted (Zero Control, PriorityClass 3 – see Wotherspoon & Wotherspoon 2003) I’m sure that it isn’t thriving.

- Balsaminaceae:

• Impatiens sodenii Engler & Warburg ex Engler 1894, a plant from tropical East Africa beingseen by W.R. Sykes in “ Islington and Rangitoto wharf. In a few places around or near old

house sites, one eminent instance being a small quarry where there were many plants. The

species generates freely from seed on Rangitoto.” It is also listed in Wotherspoon &Wotherspoon (2003), and again I have failed to observe.

- Commelinaceae:

• Tradescantia cerinthoides Kunth 1843 indigenous to northern Argentina and southern Brazil(referred in New Zealand mostly as Tradescantia blossfeldiana), and is a sub-succulent plant




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with trailing stems seen only in Islington – a small patch near an old house site. W.R. Sykes’sarticle is the first report showing this plant as adventive in Rangitoto.

• Tradescantia fluminensis J. M. Vellozo 1829 – I have also omitted this South Americantrailing plant with succulent stems (not mentioned by W.R. Sykes at all) although I haveincluded it in my 2005 and 2007 Romanian articles on succulent adventive plants (Zimer2005b, Zimer 2007b) which shows actually some inconsistency from my side. This is anextremely invasive plant which can cause a lot of trouble and inconvenience (to put it mildly)when you are all set to control it. But for the delight of the conservation personnel this plantwas eradicated from Rangitoto by 2006, which is a real achievement. The Wandering Jew is aproblem weed in Northland.

- Crassulaceae:

• Bryophyllum aliciae (Hamet) A. Berger 1930 – a Madagascar plant not known to beadventive anywhere else in New Zealand. “ Islington. On an old house site where it persists

as a relic of cultivation.”

• Crassula decumbens C.P. Thunberg 1794 is a small South African and Australian plantobserved near Rangitoto wharf “where it grows on open lava field near coastal track ” andwas sometimes confused with the similar native Crassula sieberiana which is also present inRangitoto, around Rangitoto wharf.

7. A severe infestation

with Tradescantia fluminensis in

Karangahape Gorge.




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- Geraminaceae:

• Pelargonium x asperum Willdenow 1800 an age-old garden hybrid of South African parents (Palargonium graveolens Aiton x pelargonium radens H. Moore) mentioned at “ Islington

and Rangitoto wharf. Around a number of old house sites where it regenerates in the vicinity

of the original plants.”

• Pelargonium x domesticum L. Bailey 1916, a garden hybrid, occurs again in Islington andRangitoto wharf. “Old house surrounds on lava banks and lava walls, and occasionally in

nearby shrub. Present in several places and is sometimes adventive to a minor extent .” W.R.Sykes also mentions that this hybrid is the very common cultivar adventive in some otherNorth Island locations which has “single rosy purple flowers with dark purple blotch”. It is acomplex hybrid with “at least three species involved ”, the Rangitoto plants displaying “more

characters of P. cucullatum (L.) Aiton”. However, the parentage of this plant is incompletelyknown.

• Pelargonium peltatum (Linnaeus) C.L. L'Héritier 1789 is indigenous to South Africa. It usedto be very common in cultivation and has been recorded in Islington, “very few plants in

scrub near old house site”. W.R. Sykes considers that it is actually a cultivar with “double

pinkish-mauve flowers” rather than the true species.

- Orchidaceae:

• Epidendrum cinnabarinum P. Salzmann ex Lindley 1831, is a terrestrial reed-stemmed Epidendrum discovered by Philipp Salzmann in Bahia (Brazil) and is probably just anothercultivation relict which is very unlikely to make it through the years – “a single, large,

tangled mat on lava pinnacle around an old house site” in Islington was noted by W.R.Sykes, who reckons it is the true species indeed and not one of the widespread popularhybrids.

As you can see that was quite a list…

e) The Sedum paealtum ssp. praealtum flower.

In Part 7 – in the chapter dedicated to the magnificent succulent corner from Yankee Wharf(Rangitoto Island) I wrote:

We have seen several times this plant during past trips in Rangitoto, but

none of them was flowering. I actually have no idea how the flower looks

like and it seems to be a rather shy flowerer.

In fact at the time I wrote this (just one or two days before my fourth visit to Rangitoto) it wascompletely true – I haven’t seen flowering Sedum praealtum ssp. praealtum. But while browsingdays later in the Islington Bay area we have seen and photographed few flowering plants. ARangitoto trip is always overwhelming and I need usually to spend few days to put some notestogether before I forget some of the details, to sort and (sometime) identify all the plants in thepictures (well, you may have guessed - it’s not only succulent flora I’m interested in). Unfortunately




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it took a bit longer than usual this time (as I write this – in May 2010 – I haven’t finished the job yet)and more, it looks like that the marvelous flowering Sedum praealtum ssp. praealtum I have seen hassimply slipped my mind. Unfortunately we were quite in a hurry not to miss the evening ferry, I

rushed taking few pictures and off we went towards the southern wharf. Part 7 went out on mywebsite without any change to the text before I have even checked and sorted the pictures takenthen, more, a stand-alone version of this chapter (6) was already in print in New Zealand Cactus andSucculent Journal at the time I realized the stammering. I take my time now to make this correction.On the other hand Sedum praealtum ssp. praealtum seems to be a shy flowerer indeed, at least here Iwas right.

XXIII. Aloe arborescens

Aloe arborescens (Linnaeus) Miller 1768 is another old-time favourite of New Zealand gardeners,still very common in Auckland, especially in the gardens of the old residential areas. But, as manyother plants, it has gone out of fashion in the last decades, being replaced in the years of the

8. A flowering Sedum praealtum ssp. praealtum , one of the pictures (and

plants…) I simply forgot about until I have sorted all the pictures taken in August 2009 on Rangitoto Island. This picture is from Islington Bay.




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“succulent mania” (70’s and 80’s here in New Zealand) by new introductions. However, it had a longcultivation history in Auckland and in other regions of New Zealand and I was very surprised tolearn by the mid 2000’s that there was no record of adventive specimens in our natural habitats. I

was in fact pretty sure that two of the (to me) obvious omissions Aloe arborescens and Crassulaovata have to be somewhere out in the wild (7).

9. Aloe arborescens – a

cultivation relict from

Western Springs

(Auckland).

10. Aloe arborescens – a

cultivation relict from

Western Springs

(Auckland). While the

above (picture taken in March 2005) still exists,

this one has been removedsince photographed (July

2009).




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I was aware of few garden relicts in Auckland area but beside their persistence these were not reallyself-maintained populations, and by being within reach of human intervention at any time notentitled to at least an adventive status. Aloe arborescens is in fact a very static plant, unable to

disperse without human assistance. It does not form seed (8), it does not propagate from leaves, and ifcontrolled it just only regenerates from rootstocks (relatively easy if not the entire root system hasbeen dug out properly) or from stem fragments or cuttings – this does not support pioneer expansionat all.

Aloe arborescens is a multi-branched leaf succulent shrub forming relatively large apical and“somewhat obliquely disposed rosettes, consisting of curved, dull grayish to bluish green leaves with

toothed margins”. The leaves are narrow and reach usually a length of 50 – 60 cm; their teeth can bewhitish or can have the same colour as the leaves. Old dry leaves are usually not persistent, except just below the rosettes. It usually branches from the base forming in time large mounds; in somecases the plants tend to lie on the ground with the tips turned upwards, in other cases the stems are

really entangled and support each other. Unbranched inflorescences with (usually) scarlet, but also -far less common - orange and yellow flowers appear profusely during the winter months. It is a fastgrowing plant but despite of the sustained mass growth in deep rich soil if unchecked it rarelyreaches 3 m height. . Aloe arborescens occurs on vast areas of southern Africa – from South Africa(Cape Peninsula, KwaZulu-Natal, Mpumalanga, Northern Province) to Swaziland, Mozambique,Zimbabwe and Malawi. It has the third widest distribution of all Aloes and is exceptionally common.Only in Zimbabwe it is a protected plant. In their natural habitat they often prefer rocky grassland,cliff faces and rocky outcrops, deep valleys and densely vegetated steeps of the afromontane forestsin medium to rather high rainfall areas (630 – 1,500 mm / year), from sea level to medium elevations(up to 1,800 m above sea level) mostly following the coastal regions. It is therefore not exactly adesert or semi-desert plant, but accepts a fair seasonal draught. They can take pretty much anything

between full sun and semi-shade.

Aloe arborescens has been naturalized in many countries, including New Zealand, but despite itscultivation success and persistence in abandoned gardens Aloe arborescens is just a casualappearance in our wild environments.

In New Zealand Aloe arborescens was recorded for the first time by Wilson in 1999, but there is nosubstantiating specimen to support this (D.J. Mahon, 2007). C.C. Ogle refers Aloe arborescens in2005 which is again mentioned in D.J. Mahon’s Canterbury Checklist (2007). However, its presenceon Rangitoto was already mentioned in 1992 by W.R. Sykes and despite publishing his account(backed up by three collections between 1989 and 1991) in a reputable publication remained largely

unknown for the public and… some of the botanists alike. You can imagine the big surprise I hadwhen I saw this plant for the first time through my binoculars at Yankee Wharf, on the eastern coastof Rangitoto Island as at that time I also have not read W.R. Sykes’ article. He mentions Aloe

arborescens around old houses in Rangitoto wharf and Islington Bay and remarkably in Wilson’sPark at the base of the crater cone. Very strange, I have failed to observe the plant in all theselocations, but saw it south of Yankee Wharf, quite far from any former bach site - a couple of wellestablished individuals, showing again rather very simplified growth forms, quite different from thearborescent growth (hence the name) we can usually see in cultivated plants. And again… I’m a bitclueless about how these plants could get here and propagate. The substrate the two plants weregrowing on was the same old lava block as any other plant here, quite different from the deep soil




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this species enjoys in our gardens. Nevertheless they were also a proof on how much these plantscould endure.

12. Aloe arborescens –

another Yankee Wharf

plant (Rangitoto) with

suckers. Sedum praealtum

ssp. praealtum is visible

on the right and Metrosideros excelsa in

the background.

11. Aloe arborescens –

two Yankee Wharf plants(Rangitoto) surrounded by

numerous Agapanthus praecox ssp. orientalisseedlings.




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The succulent flora of Rangitoto is actually represented only by small to medium sized succulentswhich rarely come close to their natural growth potential and this is not without a reason I think. As Ialready stated several times the black basaltic lava fields can get extremely hot in high summer,

especially in full sun… and it is quite sunny here for the average New Zealand conditions, with 49 -51% sunny hours. There is no water on the island and also there is virtually no soil in the areas wheresucculent plants usually occur to retain the precious moisture for a bit longer. Bigger succulents needof course more water and… this is actually the problem, even if the rainfalls are fairly high, withyearly averages thought to be slightly higher than in Auckland’s central areas, possibly up to 1,100 –1,200 mm / year. Big succulent plants or plants with a fast growing pace have a problem – I haveseen in several occasions how Aloe maculata or Carpobrotus edulis (if growing on the lava blocksand not in sand) have died without being able to grow and develop to their full potential. Of coursethe Aloe arborescens plants I have seen here were much reduced, but still significantly bigger (andtherefore having much higher water needs) than all other succulent plants, and they still had by farthe biggest vegetation mass from all, with only one notable exception – Agave americana.

13. Aloe arborescens – close-up of a Yankee Wharf plant (Rangitoto).




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However, Aloe arborescens has not only proved that it can be very persistent and enduring in semi-wild conditions of abandoned gardens, but also successful in extreme environments. The onlyproblem – a very reduced potential of unassisted propagation and forming of self-maintaining

populations.

Anyway, it is still a mystery for me how could this plant settle here in Yankee Wharf… If you arehunting naturalized succulents this is the place to go on Rangitoto. On relatively large surface verycomposite vegetation has established. There is a picture that I particularly like – showing fourdifferent tiers of succulent / xerophyte South African plants growing within couple of meters. This isthe uniqueness of Yankee Wharf – the strange association of very different plants of differentecology and specific cultivation needs, because I challenge anyone who would pretend that this kindof vegetation patterns can be observed in their original habitats.

Yankee Wharf and the surrounding areas have a history of human interventions – roads have been

build, quarries were active many decades ago, military installations were built during WW2; all theseactivities have produced and dispersed large amounts of “abnormally fine substrate, such as crushed

rocks” in the area pre-setting all the conditions for different vegetation development paths and hasonly increased the natural variations of the texture of the aa lava flows with a direct effect on thevegetation patterns in Rangitoto (Andrea Julian, 1992). This explains the huge variety of exoticplants in the area, but still cannot explain how the static Aloe arborescens could establish here, quitefar from the holiday baches – the source of the very most exotic succulents and xerophytes on theisland.

XXIV. Notes on Aeonium ‘Rangitoto’ (II)

Well, there’s more potentially upsetting news but there is some good news as well, so in the end it’sall good I guess (as one movie character once said). The bad news is that I had to find out – the hardway - in early autumn 2010 how sensitive Aeonium ‘Rangitoto’ to collar rot can be. All my outdoorsplanted specimens were affected, including the one designated to be my prime study specimen andfrom which I would have expected to see the flowers in one or two years (well, that’s too bad!). Bythe same time I had another 5 or 6 smaller potted plants of which just one has been affected by thisdisease (9). March and April 2010 saw me cutting and chopping the affected plants in order to save asmany cuttings as possible. At least I have this covered – I have now enough plants to release thiswinter (that’s one of the good news).

However, despite this setback there were some other positive developments as well. After the firstnotes on Aeonium ‘Rangitoto’ being published on my website in the part 7 of Succulent plants from

down under – Adventive Plants, on the International Crassulaceae Network forum, in Avonia-News 2009-11, in Romanian version on ACC Aztekium’s website and being (still) due to appear in NewZealand Cactus and Succulent Journal, there were however few feedbacks ranging from skepticism(Eduardo Carbonel and Félix Loarte of Spain) to neutral (Giuseppe Tavormina of Italy) to somesupport of my theory. For a quick refresh – I have maintained that Aeonium ‘Rangitoto’ is abackcross of a plant identified as Aeonium haworthii x Aeonium undulatum (= Aeonium ‘IslingtonBay’) by Giuseppe Tavormina to Aeonium haworthii. Ray Stephenson considered upfront that myplant is an ordinary Aeonium haworthii x Aeonium undulatum hybrid, after a second set of picturesbeing posted on ICN and sent to him by Margrit Bischofberger, he admitted seeing signs of




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backcrossing (you can imagine how delighted I was). His second opinion was in support for mytheory, but things have not stopped here. Nick Perrin (the editor of NZCSJ, to whom I also sent a liveplant) has emailed all the stuff he’s got from me by late 2009 to Rudolf Schulz to hear the opinion of

another authentic Aeonium connoisseur. With Rudolf being probably overseas we didn’t get themuch wanted feedback for many months but a second email was answered to in less than 24 hours bymid April 2010. Here’s the core of Rudolf’s feedback: “ I have no trouble in accepting Eduart's

conclusions. There is a lot of guesswork as to the parentage because there are no comments on

flowering and without that it’s all just guesswork. I am pretty convinced that the A. haworthii x

undulatum is correct but from there it’s just guessing. I would assume that the 2x plants in question

which he proposes to name could just as well be F2 offspring from the fertile hybrids showing more

of the dominant A. haworthii traits. From what I have seen around the road cuts in Miramar,

Wellington, similar plants are not uncommon.”

Oh, how I wish I would have observed the flowering! But as it looks now this prospect has beenpostponed again for at least a couple of years. Rudolf Schulz comes up actually with a differenttheory. In his second scenario Aeonium ‘Islington Bay’ would be the F1 hybrid of Aeonium

haworthii and Aeonium undulatum, while Aeonium ‘Rangitoto’ is the F2 hybrid displaying more

14. Aeonium ‘Rangitoto’ in full vegetation (August 2009).




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accentuated Aeonium haworthii traits due to genetic dominance. I have pretty detailed pictures of an Aeonium ‘Islington Bay’ flowering, from now on it’s just a waiting game for the flowering of Aeonium ‘Rangitoto’.

15. Aeonium ‘Rangitoto’in full vegetation (August

2009).

16. Aeonium ‘Rangitoto’in full vegetation (August

2009) – detail withemerging new rosettes.




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However, by August 2009 Aeonium ‘Rangitoto’ was in its prime, considering it is mid to late winterhere. The plant designated for study was in full growth. The rosettes were up to 18 – 20 cm diameter(the main rosettes, of course) but usually less, and had up to 30 well formed leaves plus up to 10

17. Aeonium ‘Rangitoto’in contrast with the true

species – Aeonium

haworthii (November

2009).

18. Aeonium ‘Rangitoto’in contrast with the true

species – Aeonium

haworthii (August 2009).




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incomplete developed leaves in the apical area (around the apical growth point). Leaves were up to11 cm long and 3.5 – 3.8 cm wide in the upper third (for leaves having maximal or close to maximallength), only 0.8 cm wide at the base but definitely much thicker here. The plant was forming at that

time a dome-like crown (40 cm diameter, 30 cm high) of 25 – 27 rosettes (very similar to Aeoniumhaworthii) most of them showing strong axillary growth, up to 7 – 8 new rosettes were appearing oneach mature rosette. The true Aeonium haworthii planted nearby for comparison was also showingaxillary offsetting, but only 3 – 5 offsets per rosette. Few months later this particular Aeonium ‘Rangitoto’ had possibly 180 rosettes and was 60 cm diameter and 45 cm high. The plant had a quitevisible main stem, vertical and almost perfectly straight and radial branches at the same level. It alsohad slightly glaucous leaves, but much greener although intensely red-edged (a thin line, but veryintense, almost wine red) compared to Aeonium haworthii.

It was definitely growing much faster and stronger than the true Aeonium haworthii. To put it in fewwords - Aeonium ‘Rangitoto’ definitely displays the habit of Aeonium haworthii, but grows much

stronger and borrows form the colours of Aeonium undulatum. Unfortunately, I have to wait for theflowers for a while…

Additional References:

R. Botha – Kranz Aloe ( Aloe arborescens) (not dated, a slideshow created for EcoPort database);

Ernst van Jaarsveld & Liesl van der Walt (Kirstenbosch Botanic Garden) – Crassula coccinea (www.plantzafrica.com, 2001);

C.C. Ogle – Adventive plants collected in the Wanganui Conservancy of the New Zealand Department of Conservation (2005) - not directly consulted;

Rudolf Schulz (personal comment April 2010);

W.R. Sykes - Succulent Plants on Rangitoto Island (in Auckland Botanical Society Journal, 1992)

E. Zimer – Aloe arborescens (www.cactusi.com Cactus Romania – Enciclopedie, 2006);

E. Zimer – Crassula coccinea (www.cactusi.com Cactus Romania – Enciclopedie, 2007);

Further Readings:

Michael L. Charters - Flora of South Africa

My Notes:

(1) Left alone it barely branches from the base, if pruned some plants start branching profusely (but some not). However, in Rangitoto I have seenmostly single stemmed naturalized plants or with merely couple of branches.

(2) It is quite rust prone, but there is really nothing you can do about.

(3) I haven’t tried to propagate Crassula tetragona this way, but I reportedly it is a proven vegetative dispersal mean, not very efficient I think butgiven a high number of tries it probably would succeed.

(4) What a coincidence of names! The 1988 Checklist is C.J. Webb’s of course!

(5) The list I am working now covers also most of the sub-succulent species.

(6) The article “The succulent corner of Yankee Wharf ” appeared in November 2009 in New Zealand Cactus and Succulent Journal.




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(7) In later years both plants have been identified and published in adventive flora checklists. However, the only botanical account placing Aloe

arborescens on Rangitoto (W.R. Sykes, 1992) remained unknown to me until… after I started to write this chapter.

(8) It could be again the excessive clonal propagation in the early years of cultivation, but I can’t exclude completely hybridization in such an old

garden plant.(9) Most of my Aeonium plants were affected – especially the hybrids Aeonium ‘Íslington Bay’ and Aeonium ‘Kiwionium’. I have never experiencedcollar rot in such an extent, it must have been the extremely wet winter, followed by a rather hot and dry summer interrupted every now and than byspell of heavy rain that has created all the conditions for the disease.

------------------------------------------------

All errors, omissions and misconceptions are mine.

Eduart Zimer, December 2009 – May 2010

http://eduart.page.tl/Home.htm

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Eduart Zimer - (SDU) - Adventive Plants - Part 9 (2010)

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