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582.922:581.4(6)

M E D E D E L I N G E N L A N D B O U W H O G E S C H O O L

W A G E N I N G E N N E D E R L A N D 77-20 1 977)

S E E D L I N G M O R P H O L O G Y O F

S O M E A F R I C A N S A P O T A C E A E

A N D IT S T A X O N O M I C A L

S I G N I F I C A N C E

J . B O K D A M

Laboratory of Plant Taxonom y and Plant Geography,

Agricultural University, Wageningen, The N etherlands

(Received 26-VII-1977)

H. VEENMAN & ZONEN B.V. W AG EN ING EN -1977

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C O N T E N T S

page fig.

1.

I N T R O D U C T I O N ,

5

2. S E E D L I N G C H A R A C T E R S 7

2.1 . G e r m i n a t i o n

7

2.2. Ro ot sys tem 7

2.3 . H y p o c o t y l

7

2 .4 . Coty ledons 8

2.5. E n d o s p e r m

9

2.6. Ep ico ty l 9

2.7. E o p h y l l s

9

3 . S E E D L I N G T Y P E S

11

4. C O R R E L A T I O N B E T W E E N S E E D L I N G T Y PEANDS O M E I M P O R

T A N T TAXONOMICAL C H A R A C T E R S

IN

SAPOTACEAE

15

5. S O M E R E M A R K SONT H E C L A S S I F IC A T I O NOFT H E S A P O T A C E A E.20

5.1.Thec lassif icat ion

of

B a e h n i

20

5.2.Theclassification of Aubrville 21

S U M M A R Y

23

RESUME

24

A C K N O W L E D G E M E N T S ..25

A P P E N D I X : D E S C R I P T I O N SANDD R A W I N G SOFTHE F O L L O W I N G

S P E C I E SOFA F R I C A N S A P O T A C E A E 27

1. Afrosersalisia afzelii ENGL.) AuBRv 29 1

2.

-

cerasifera

(WELW.)A U B R V

29 1

3.Aningeria adolfi-friederici

( E N G L . ) R O B Y N S

et

G I L B E R T

31 2

4.

-

altissima

(A.

C H E V . ) A U B R V .

e t

P E L L E G R

33 2

5.

-

robusta

(A.

C H E V . ) A U B R V .

et

P E L L E G R

33

6. Argania spinosa(L.)SKEELS 34 3

7.

Aubregrinia taiensis

( A U B R V . etP E L L E G R . ) H E I N E 34

8.

Autranella congolensis ( D E W I L D . )

A.

CHEV 36 4

9.

Baillonella toxisperma PIERRE 38 5

10 .Breviea leptosperma (BAEHNI) HEINE 38

11 .Butyrospermumparadoxum GAEKTN.F.)HEPPER 40

12.

Chrysophyllum

azaguieanum M I G E

42 6

13 .- giganteum

A.

C H E V 42 7

14 .- muerense

E N G L

44 8

15.

Donella ogowensis

(A.

C H E V . ) A U B R V .

et

P E L L E G R

44 9

16.

-

pruniformis ( P I E R R E

ex

E N G L . ) A U B R V .

et

P E L L E G R

46 9

17.

-

ubanguiensis (DEW I L D . ) A U B R V

48 10

18. -

welwitschii ( E N G L . )PIERRE

ex

A U B R V .

et

P E L L E G R

50 10

19.Gambeya beguei ( A U B R V .

et

P E L L E G R . ) A U B R V .

et

P E L L E G R

50 11

20. -

boukokoensis A U B R V .

et

P E L L E G R

52 12

21.

-

lacourtiana (DEW I L D . ) A U B R V.

et

P E L L E G R

54 13

22.

-

perpulchra (MILDBR.)A U B R V .etP E L L E G R

56 14

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page fig.

23 .Gambeya subnuda ( BAK .) PIERRE 56 14

24. Gluema ivorensis

AUB R V.

et

PELLEGR

58

25. Ituridendron bequaertii D EW I L D 58 15

26. Kanton guereensis

AUB R V.

et

PELLEGR

60 16

27 .

- sp 62 16

28 . Malacantha alnifolia

(BA K.) PIERRE

62 15

29. Manilkara obovata

(SABINE

et

G.D O N )

J. H.

HEMSLEY

(=M.lacera

(B AK. )

D U B A R D )

63

30.

Mimusops

sp

63 17

3 1. Omphalocarpum elatum MIERS 65

32..-

lecomteanum P I E R R E

ex

E N G L

66 18

3 3 .- procerum

P.

BEAUV 68

34.- sp 68

3 5.

Pachystela bequaertii

D E

W I L D 69 19

36.

-

brevipes

( B A K . ) E N G L

71 19

37.

Pseudoboivinella oblanceolata

(S.

M O O R E ) A U B R V .

et

P E L L E G R

71

3 8 .

Synsepalum dulcificum (SCHUM.) BILLON

72 20

39. -

stipulatum ( R A D L K . ) E N G L

72 20

40.- subcordatum D EW I L D 74 20

41 .

Tieghemella africana PIERRE 74 21

42 .- heckelii PIERRE 76 21

43 . Tridesmostemon claessensii D E

W I L D 77 22

44 .- omphalocarpoides E N G L 77 22

45.

Tulestea seretii

(DE

W I L D . ) A U B R V .

et

P E L L E G R

79

46. Wildemaniodoxa laurentii( DE

W I L D . ) A U B R V .

et

P E L L E G R

79 23

B I B L I O G R A P H Y

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1. I N T R O D U C T I O N

S e e d l ings

are

s t u d i e d

for two

r e a s o n s m a i n l y . F i r s t

of all

t h e r e

is an

u r g e n t

n e e d a m o n g s t p l a n t e co l o g i s t stoiden t i fy se ed l ing s f romac e r t a in r e g ionor

h a b i t a t .Toe na b le t h i s , s e e d lings ha ve b e e n de sc r ibe dandfigured,andiden t i f i

c a t i o n k e y s h a v e b e e n c o m p o s e d , in t e m p e r a t e r e g i o n s

(LUBBOCK,

1892;

K I N G , 1966; C S A P O D Y , 1968;

M U L L E R ,

in prep.) as well as in the tropics

( T R O U P , 1921; D U K E , 1965; D E LA M E N S B R U G E, 1966; B U R G E R , 1972; D E

K O N I N G ,inp r e p . D E VOGEL,inp r e p . ) . M o r e o v e r , m o r p h o l o g i c a l c h a r a c t e r s

m a y ha v e e c o log ic a l s ign i f i c anc e . T R O U P(1921) ,R I Z Z I N I (1965)andJACKSON

(1968)e m p h a s i z e d t h a t s ee d li n g m o r p h o l o g y s h o u l dbeh o r o u g h l y i n v e s t ig a t e d

fo rab e tt e r c o m p r e h e n s i o nofg e r m i n a t i o n , e s t a b l i s h m e n tandu v e n i l e g r o w t h

d u r i n g

the

n a t u r a l r e g e n e r a t io n

of

ve ge t a t i on .

Inthes e c on d p l a c e s e e d l ingsares t u d i e d b e c a u s e t h e y p r o v i d e a d d i t i o n a l

i n f o r m a t i o n

to our

k n o w l e d g e

of

he life cycle

of

p l a n t s .

It s

ge ne r a l l y a c c e p te d

t o d a y , t h a t t a x o n o m i c a l r e s e a r c h s h o u l d

not be

based exc lus ive ly

on

m o r

p h o l o g i c a l c h a r a c t e r s

of the

m a t u r e s p e c im e n s ,

but

a l so

on

c h a r a c t e r s

of the

j uve n i l e s t a ge soft h e p l a n t . C r i t ic a l e x a m i n a t i o nofc o r r e l a t i o n s b e t w e e n b o t h

g r o u p sofc h a r a c t e r shas r e su l t e d r e pe a t e d ly in a b e t t e r u n d e r s t a n d i n gof

t a x o n o m i c a l l y d if fi cu lt t a x a . D E

CANDOLLE

( 1825 )was hef irs t bo ta n i s ttouse

s e e d li n g c h a r a c t e r sfor thed e l i m i t a t i o noft r i be sandg e n e r ain Leguminosae.

U n f o r t u n a t e l y , v e r y

few

b o t a n i s t s f o l lo w e d

his

e x a m p l e

(e.g.

GUILLAUMIN,

1910) .

In he

p a s t

two

d e c a d e s h o w e v e r ,

the

n t e r e s t

in

u s ing s e e d l ing c ha r a c t e r s

fo r t a x o n o m i c a l p u r p o s e s

has

r ev ived (VASSILCZENKO, 1 93 6 ; D EFERR,

1952;

L O N A R D , 1957; C E R C E A U - L A R R I V A L 1962; J A C O B S , 1966; W E B E R L I N G and

L E E N H O U T S ,

1966;

B R E T E L E R ,

1973;

B A U D E T ,

1974). More details about the

h i s t o r yofb l a s t o g e n y ( s t u d yof thed e v e l o p m e n tof thes e e d l ing )areg iven

byJACOBS(1966) andB A U D E T(1974).

In Sapotaceae, as inLeguminosae, thed e l i m i t a t io nofsub f a m i l i e s , t r i b e s

a n d g e n e r aisr a t h e r c o m p l i c a te d . R e c e n t m o n o g r a p h sandr e v i s ionsofA f r i c a n

Sapotaceae

sh ow wi de d i f fe rences

in

o p i n i o n :

MEEUSE,

1960, 1963;

HEIN E,

1 9 6 3 ; AuBRviLLE, 1964, 1974; B A E H N I , 1965; HEMSLEY, 1968. A common

c o n c e p t s e e m sto bea b s e n tandc o n f u s i o n a b o u tthep r o pe r c l a s s i f i c a t ionand

n o m e n c l a t u r e r e i g n s .Fort h i s r e a so nani n v e s t i g a t io nof thes e e d li n g m o r

p h o l o g yof he A f r i c a nSapotaceae s ee m s o p p o r t u n e .

I n t h i s pa p e r ,

46

spec ies

outof

25 ge ne r a h a ve be e n s tud i e d . M os t spe c ie s

are

f r o m W e s tandC e n t r a l A f r i c a .Theseed l ings w ere e i the r d i rec t ly co l lec tedin

the fieldoro b t a i n e d a f t e r s o w i n gin an u r s e r yinK i s a n g a n i ( Z a i r e )or in the

c o n s e r v a t o r yatW a g e n i n g e n ( N e t h e r l a n d s ) . S p e c i m e n s h a v e b e e n c o n s e r v e das

h e r b a r i u m

or in

sp i r i t

at he

H e r b a r i u m V a d e n s e ( W A G ) . O t h e r se e dl in g s h a v e

be e n s tud i e dat the H e r b a r i u mof theN a t i o n a l I n s t i t u t e for A g r i c u l t u r a l

Sc iences

at

Y a n g a m b i , Z a i r e ( Y B I ) ,

or

h a v e b e e n k i n d l y m a d e a v a i l a b l e

by he

H e r b a r i u m

of the

N a t i o n a l B o t a n ic a l G a r d e n s

of

B e l g i u m ( B R ) .

My

o b s e r v a -

Meded.

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Wageningen

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tions have been suppleme nted by inform ation from literature, studied mainly

in the W ageningen La bora tory for Plant Tax ono my , where I found working

facilities du ring my tem po rary assignm ent on the Staff and thereafter.

Collection an d subseq uent de scription too k place wh en the seedlings had

developed 2 -3 green herbaceo us leaves. Dim ension s and colou rs refer to dry

material, unless stated otherwise. The organs of the seedlings have been

described according o

S.A.C.D.B.T.

( A N O N . ,1962).A sregards henervation of

cotyledons and leaves, he termino logy of

H I C K E Y

(1973) was used. F ine details

were observed by 40 x ma gnification, while trans luce nt dots, lactiferous d ucts

and minute nervation patterns have been observed in transmitted light.

Joined cy tological research has been carried out by

A R E N D S

(1976).

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2.S E E D L I N G C H A R A C T E R S

2 . 1 .

G E R M I N A T I O N

G erm inatio n starts with the abso rptio n of wa ter, followed by swelling and

grow th of the emb ryo. Th e increasing volum e of the seed conten t causes the

testa to rup ture at the micropy lar end. Two linear cracks are formed on the

ven tral side of the seed, one on each side of the scar. Th e zone between these

two crack s, consisting mainly of the scar, is push ed o utw ards by the growing

em bryo as a variably-sh aped valve (seefig.4: 2) . The first organ w hich emerges

from the esta is he radicle hisente rs he soil,anchoring theem bryo. Next the

hypoco tyl is prod uce d, at first in the shape of a bent k nee, but soo n it stretches

and becom es erect, pulling the cotyledons out of the surro und ing endo sperm

and testa, or, if adh eren t, lifting b oth . Du ring liberation from the testa, the

foliaceous coty ledons ex pand strongly, fleshy co tyledons h ardly o r not at all.

In some species the hypocoty l does n ot de velop. The fleshy cotyledon s ofsuch

species either simply unfold or they rem ain enclosed w ithin the testa. Th e

seedling is considered to be in the cotyledon stage w hen the cotyledon s have

been ex pan de d (vs. rem ain in the testa), but the first leaves have n ot yet devel

oped. The eophyll stage is reached, when the first leaves (eophylls) have

developed.

Ge rm inatio n s tarts between eight and a hu nd red days after fruit sh edding

( D E L A

MENSBRUGE,1966). Th e cotyledo n stage ma y last from several weeks

to some years. RIZZINI (1965) observed a 2 year-long cotyledon stage in

Pouteria torta

MART.,a species of periodically burn ed savan nas, with th e

cotyledo ns persistent within the testa.

2.2 . ROOT

SYSTEM

All the observed seedlings have a well developed taproot. In

Argania

spinosa*,

a species from the No rth ern Sah ara, the tap roo t is very long (up to

45 cm in the eoph yll stage) and slender.Butyrospermum paradoxumfrom the

Sudan savana has an extremely stout and wood y tapro ot. T he colour of the

roo ts isalways whitish, turning bro wn after dry ing.

2.3 .

HYPOCOTYL

The rootcro wn , i .e . the transit ion between the taproo t and the hypoco tyl ,

isno t always clearly recognizable, but n orm ally it iswell m arke d by chan ges in

* Fo r auth ors nam es the reader is referred to tabel 2which is mainly b ased on the classi

fication of AuBRviLLE, 1964. n some ab erra nt cases hese nam esare mentioned in he text.

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structure and co lour of he epidermis or by a change in shape . In seedlings with

a long hypoco tyl the roo tcrow n isusually str aigh t, while in species with a s hor t

or absen t hyp oco tyl, it soften genicu late (seefig.7 : 3 , resp .fig.2 0 : 1 ,6).

The length of the hyp ocotyl varies considerably. InOmphalocarpumand

Autranella

it may exceed 20 cm , while in

Butyrospermum

and

Synsepalum

it is

quite or nearly absent. D urin g germ ination it is cylindrical and green, but in

the cotyledon stage it may becom e woody, brow n and qua dran gular, as is the

case in a.o.

Omphalocarpum, D onella

and

Gambeya.

In these genera only the

extreme apex of the hypocotyl rem ains green and herb aceo us, show ing two

lateral longitud inal

slits.

Thisapicalportion m ay beconsidered as he prolonga

tion of the petioles of the cotyledo ns, which have beco me coalescent with the

base of the epicotyl. Fo r prac tical purpo ses how ever, I treat it here as the apex

of the hyp oco tyl. In fresh m ateria l it is inflated, in dry mate rial it is na rro w er

than the rest of the hypocoty l. Du ring theeophyllstage or later, the en tire

hypoco tyl becomes w oody an d once mo re cylindrical. It isalways glabrous.

2.4. COTYLEDONS

Th e main criteria used for thedescription of he cotyledon s are their position

in relation to the esta and their texture.

Seedlings with free cotyledon s are called ph ane roco tylar . Th e position of

their cotyledons m ay be hor izon tal or slightly erect. In crypto cotyla r seedlings

the cotyledons rema in enclosed in the testa

( D U K E ,

1965).

Acc ording to their texture thecoty ledo ns of the studied tax a can be classified

asfollows

A. Co tyledons foliaceous, nervation a cro-b roch idod rom ous .

1. Co tyledo ns pap yrac eou s, dark green, mu ch enlarging dur ing and after

liberation from the testa and the end osp erm , long persistent, asymm et

rical , base abruptly narrowed into a petiole; venation system con

spicuous.

2. Co tyledon s coriaceo us, dark to light green, enlarging during an d after

liberation from the testa and the endo sperm , less persistent, slightly

or not asymm etrical , base abruptly narrow ed into a petiole; v enation

system inconspicu ous.

B.Cotyledons fleshy, nervation indist inct , hy pho dro m ous .

Co tyledo ns thick, plano-con vex, light to dark green in pha nero coty lar

seedlings,pale yellowish green to bro wn in crypto cotyla r seedlings,

symmetrical or asymmetrical, caducous to rather persistent (in cryp

tocoty lar seedlings).

The asy mm etrical shap e of the cotyledon s is caused by the shape of the seed

an d it isexpressed in the following features (see fig.4 3 ,4 ) :

- the blade halves on either side of the m idrib are unequ al

- the m argin of the bro ade st blade half is either concave or straight, in

stead ofconvex between the m iddle and the apex of the cotyledon

8

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- them idrib terminates in he marg in beside the apex of he cotyledo n.

The surface is glabro us bu t on bo th faces of foliaceous cotyledo ns m inute ,

colourless papillae can be observed w ith strong m agnification. In some species

lactiferous d ucts are visible in tran sm itted light. Stipules are never pre sent.

2.5. ENDOSPERM

According to

BOLD

(1973,p. 593), presence and q uan tity of endosp erm in

germ inating seeds depen ds rath er mo re on the degree to which it has not been

absorb ed by the em bryo during its develop me nt, tha n on the degree inwh ich it

has been produ ced . In the studied taxa of AfricanSapotaceae,the quantity of

endosperm varies from abu nda nt Omphalocarpum, Tridesmostemon,Manil-

kara) to deficient

Tieghemella,

Afrosersalisia), while endo sperm is lacking

com pletely in

Baillonella,

Synsepalum

and some oth er genera. Even in seeds

from yo un g, green, develop ing fruits ofSynsepalum dulcificumno endosperm

could be found.

Th e textu re of the white endo spe rm is soft an d fleshy in fresh seeds, it

becom es coriaceous in dry seeds. Du ring the liberation of the cotyledons from

the testa, the endosp erm may rem ain adhe rent for some time on their surface

near the apex. It soon shrivels and becomespalebrown and m embranaceous.

2.6. EPICOTYL

In nearly all species the epicotyl is distinct, straight, slender and either

cylindrical or compressed. It may be long ( > 4 cm) or sho rt ( < 4 cm). This

limit at 4 cm w as chosen after ep icotyl length of seedlings with foliaceous

cotyledons was com pare d w ith tha t of seedlings with fleshy one s. Usually an

indumentum of variably developed medifixed hairs covers the epicotyl.

Late ral bu ds ma y be observed in the axils of the coty ledon s and also in the

axils of cataph ylls, brow n scale-like rudim enta ry leaves which are present in

some species. Fro m both types of buds new shoo ts may develop after des truc

tion of the apical bu d.

2.7. EOPHYLLS

The first well developed green leaves are called eop hylls( D U K E ,1965).They

may be opp osite or alterna te, provided with stipules or not, while their texture

is either papy raceo us o r coriaceous. Th e petioles are short to rathe r long, e.g.

up t o 1.5 cm in Tieghemella africana.They are variably shaped and rarely

glabrous. Translucent dots have been observed in

Aningeria, Ma lacantha,

Chrysophyllum giganteum a ndChrysophyllum muerense.Lactiferous duc ts are

visible in transm itted light in man y species. The ne rvation may be eu cam pto -

Meded.

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drom ous or brochido drom ous with or without formation of an intramarginal

vein. Only inM alacantha and

Butyrospermum

the venation is craspe dodro -

mous.

As he nerv ation patt ern in foliaceous cotyledons is

(acro)brochidodromou s,

the difference in nerv ation b etwee n the coty ledo ns and th e eophy lls is consid er

able when the eophylls have crasped odrom ous n ervation or bro chido drom ous

nervation w ith an intram argina l vein.

10

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3 . S E E D L I N G T Y P E S

In the available seedling classifications the ma jor c riteria are the position of

the cotyledons in relation to the soil surface after germination and their

liberation from the testa. The correspon ding term inolog y, derived from agri

cultura l practices, distinguishes epigeal and hypo geal ge rmin ation , resulting in

seedlings with the cotyled ons abo ve an d below the soil surface respectively.

Am ong the taxa studied I never found seedlings with the cotyledon s below

soil surface in the field. Th e germ inatin g seeds were inva riably lying on to p

of the soil, often still enclose d in the m ou lde ring fruit or in du ng of m on ke ys

and elephants. However, when seeds of taxa with a short or undeveloped

hypocotyl , are sown at considerable depth, the cotyledons may rema in buried

irrespective of their liberation from the testa. Examples of the latter are

Pachystela,Wildemaniodoxa

andBaillonella:their seed lings are epigeal in the

field, bu t may be hyp ogea l when sown at con siderable d ep th. B ecause of this,

I prefer the criterion and the term inology ofDUKE(1965), w ho distinguishes

cryp to- and pha nero coty lar seedlings (see 2.4), bu t this criterion sho uld be

applied w ith care as well. Tax a, which have pha nero coty lar seedlings with a

short or undeveloped hypocotyl in the field may produce seedlings with

slightly exp and ed c otyle do ns if heir seeds are sown in a solid heavy soil, wh ich

hamp ers heunfolding of hecotyledons.

LONARD

1957)arran ged he seedlings

of some ribes of

Ca esalpiniaceae

nto four types,which ma y be reduced to two ,

following th e conside rations a bov e. His type B (cryptoc otylar, hy pogeal) is

identical to type D (cryptoc otylar, ep igeal), but the seeds ofBhave been sown

at considerable d epth . His type C (phaneroc otylar , epigeal, hypocotyl not

developed ) sbut avaria nt ofA pha nero coty lar, epigeal,hypoco tyl developed).

Th e taxon om ical value of the length of the hyp ocotyl m ay be very limited in

certain grou ps. I t has been demo nstrated byLA M PRECH T(1945, 1948, quo ted

by

BA U D ET,

1974) ha t the difference between the well develope d hyp ocotyl of

the phanerocotylar seedling ofPhaseolus vulgarisL. and the undeveloped

hyp oco tyl of the crypto coty lar seedling ofPhaseolus coccineusL. was based

on oneallelonly. Hyb ridizatio n of the two species was easy and it produ ced

heterozygotic phanerocotylarFiseedlings with short hypocotyls, i.e. inter

med iate between the paren ts .

This show s tha t the difference b etween the ph ane roco tylar an d the cry pto

cotylar seedlingaswellas ts axo nom ical significance m ay be ess funda me ntal

than is pointed ou t by

L O N A R D ,

I.e., when he conc lude s: 'Les plantules d e

tou tes lesespcesd 'un mme "b on " genreprse nten t lemme ypede structure,

ou, en d'au tres termes, au sein de chaque " b o n " genre domine un seul type de

pla ntu le'. The v alidity of this rule has been criticized alread y by

JACOBS

(1966)

on the assum ption th at charac ters m ay have different taxono mical weight in

different tax a.

Th e delimitation of major seedling types should be based preferably on

Meded.

Landbouwhogeschool Wageningen 77-20 1977)

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cha racters withfylogeneticsignificance.

It

ap pe ars from this study (4), tha t

in

Sapotaceaethetextureof thecotyledonsissuchacharacter .It isclosely

related

to he

eduction

of

endosperm,

a

reputed phenome non

of

evolutionary

advancement in Dicotyledons

(TAKHTAJAN,

1969;

CRONQUIST,

1968). The

seedlings

of

Sapotaceae

can beclassified

in

his way into two basictypes

A : Seedlings with foliaceous cotyledons,developing from seeds with a bu nd an t

endosperm.

B:Seedlings with fleshy cotyledons,

developing from seeds with scanty

orno

endosperm.

These two types may

be

urthe r divided

in

view

of

he escape

of

he cotyledons

fromthetestaand thedevelopmentof thenervation, b oth ch aracters being

closely relate d

to

he function

of

hecotyledons

A l. Omphalocarpum type:

phane rocotylar ; hypocotyl long; cotyledons papy

raceous, strongly enlarged, dark green, persistent witha conspicuous

nervation, dom inan t functions absorption

and

assimilation.

A2. Argania type:

phanerocotylar ; hypocotyl long

to

short ; cotyledons

coriaceous, enlarged, da rk

to

light green, pe rsistent

to

rather caduc ous,

nervation conspicuo us

to

nconspicuo us, do m inan t functions ab sorptio n,

storageand assimilation.

B l. T ieghemella type:

phan erocotylar ; hypocotyl long

to

sho rt ; co tyledons

fleshy,notenlarged, caduc ous, dar k greentopaleyellowish-greenor

brow n, nervation inconspicuous, dom inan t functions storage and assimila

tion.

B2.Butyrospermumype:cryptocotylar ; hypocotylnotdeveloped;cotyledons

fleshy, persisten t,paleyellowishtowhite, dom inan t function storage.

Some less impo rtant characters are correlated w iththeseedling type

a thequad rangular shapeofhe hypocotylin hecotyledo n stageisfound

onlyinAype seedlings

b :theepicotylin the Btype, p articularlyin the B2type,isco nsiderably

longer han theepicotyl n he

A

ype,whichhas

a

onghypocotyl .

In

both

typestheassimilating parts ,i.e. thecotyledons resp.theeophyllsare

elevated

c cataphyllsarepredo mina ntly foundinB2y pe seedlings

dopp osite eophylls are only found inBlseedlings.

By using ch aracters suchasphyllotaxisofhe eophylls, presenceofca taphylls

and

the

length

of

the first intern od e, further subdivision

of the

four types

is

possible.This,how ever, doesno t seemoppor tune

for

his study.

A prelimina ry surveyof theseedlingsofdicotyledonou s taxa other than

Sapotaceae

show s th at different seedling types

aremet n he

primitive

Mag-

nolialesand hemore advancedAsterales.In heMagnoliales3different types

should be me ntioned here

12

Meded.LandbouwhogeschoolWageningen 77-20 1977)

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- P y c n a n t h u s t y p e :c r y p t o c o t y l a r ; h y p o c o t y lnotd e v e l o p e d ; f r o m s e e d s w i t h

a b u n d a n t r u m i n a t e e n d o s p e r m

and

w i t h

a

m i n u t e e m b r y o ; c o t y l e d o n s

p a p y r a c e o u s , d o m i n a n t f u n c t i o n a b s o r p t i o n . O c c u r s in

Pycnanthus

angolensis

( W E L W . ) W A R B .

-

Mo no do ra t y pe:

l ike

Pycnanthus,

but

w i t h d e v e l o p e d h y p o c o t y l ; o c c u r r i n g

inMonod ora brevipes B T H . ,Mono dora crispata E N G L ,

et

DIELS, Annona

muricata

L. and in

Annona reticulata

L.

The

c o t y l e d o n s

maybe

l i b e ra t ed

s o m e t i m e s ,butu s u a l l y t h e yaret o r noff,b e i n g u n a b l etoe s cap e f ro mthe

r u m i n a t e e n d o s p e r m

and the

t es ta , l ea v ing

two

o p p o s i t e s c a r s

on the

s eed l i n g s t em .

-

Cananga type:

p h a n e r o c o t y l a r ; h y p o c o t y l d e v e l o p e d ; c o t y l e d o n s p a p y

race o u s , s t ro n g l y en l a rg ed , d a rk g reen , p e r s i s t en t , n e rv a t i o n c o n s p i cu o u s ,

d o m i n a n t f u n c ti o n a b s o r p t i o nanda s s i m i l a t i o n . D i f fe r s f ro mthe

Ompha-

locarpum

t y p eby them i n u t e e m b r y oin these e d . O c c u r r i n gin

Cananga

odorata

( L M K . )

H O O K .F.etT H O M S . , ( B U R G E R ,1972), and inAnnona squa

mosa

L.,( D U K E ,1965 andG I L B E R T ,1939).

Inthe

Asterales

the o l l o wi n g t y p e h as b een fo u n d:

-

Astera les type:

p h a n e r o c o t y l a r

;

h y p o c o t y l d e v e l o p e d ; c o t y l e d o n s f o l ia c e o u s ,

e n l a r g e d , g r e e n , w i t h i n c o n s p i c u o u s n e r v a t i o n , d o m i n a n t f u n c t i o n s

s t o r a g e

and

a s s i m i l a t i o n .

In t ab l e1 thes eed l i n g ty p es m en t i o n ed h e reares u m m a r i ze d ;thef igures

a re s ch em a t i c .

Meded.

Landbouwhogeschool Wageningen

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c

S P

0 0

e

o .

ca

ft

S

o

co

U

ffl

C

O 3

pa

o.

o.

ft

ft t -

8

a

O

ca

6 0

o

ca

c

U

+ -

H

ca

U

c C o

+

M

s

+

ft

+

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+

o

"o o~^~

a ui ,

ca +

ft

+

e

a

c

e o

2'

S ca

ftrs

s

a

B-o

2

.

- - T ; i S c s

P H-*-*

t l .

-t-> O

0

*

> O 1)

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n

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-*-

ca

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t l

6 0 c

CJ

u

o

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c

c

c

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4.

C O R R E L A T I O N B E T W E E N S E E D L I N G T Y P E A N D

S O M E I M P O R T A N T T A X O N O M I C A L C H A R A C T E R S

I N S A P O T A C E A E

Th e au th or s of the available classifications inSapotaceae(see Introdu ction )

used mo re or less the same set of chara cters. Ho wever, dissimilar opinion s

ab ou t the taxono mic al weight of the characters used led to different applica

tions and resulted in widely different systems. A bet ter kno wled ge of the varia

tion patter n of the chara cters in question and un dersta ndin g of their mu tual

corre lation may help o obtain a consensus of opin ion. Therefore a com pariso n

ha s been ma de between the variation of the seedling and of othe r c harac ters

used for the classification ofSapotaceae(seeTa ble 2).

No correlation seems to exist between seedling type and the following

characters

2.

habi t ;

3 .

venation pa ttern of the eop hylls;

4.place of the inflorescences

5.presence of unisex ual flowers

6. nu m ber of calyx who rls

7.

coalescence of the sepals

8. presence of bracts un der the calyx;

9. relative length of the corolla tu be ;

10.presence of dors al appenda ges on the pe tals;

11 . num ber of corolla lobes

12.n um ber ofstamens

13 .num ber of staminodes.

ad 3. N o difference has been observed between the vena tion patter n of the

eophylls and the venation of leaves from adult specimens. B rochid o-

dro m ou s venation with num erou s parallel secundary veins, divergent

from the mid rib at widely acute or right angles, and unitin g in an intra

m arg inal vein, is a striking feature of several species. It may be c on

sidered asa m ore advanced ch aracter, whilea brochidodrom ous pat tern

without an intramarginal vein and few looping secundary veins,

divergent at an acute angle should be considered as more primitive

( T A K H T A J A N ,1969).The first type with an intra ma rginal vein has been

found in taxa with both seedling types: Wildemaniodoxa, B-type;

Englerophytum, prob ably also B-type;Donella, AutranellaandManil-

kara,

all A-ty pe.

ad 4. Cau liflory occurs in taxa with A-type seedlings as well as in tax a with

B-type seedlings:O mphalocarpum,A- type ;

Englerophytum, probab\y)

B-type.

Meded.

Landbouwhogeschool Wageningen

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