Chemosystematics

Pigments often unstable Environmental variation (pH;

elevation modifies blue colors)

Reasons why plant pigments have been used in systematics only during the last 50 years:

4 main types of pigments:

1. Anthocyanins 2. Yellow flavonoids 3. Colorless flavonoids 4. Betalains

*First 3 are flavonoids and unrelated to betalains

Flavonoids: most important source of nongreen coloration; Benzene ring structure with side chains = infinite variety

• important in yellow flowers• important in blue flowers• important in white flowers

Delphinium (larkspur)

Lisianthius nigrescens

Alcea rosea nigra

Salix gracilistyla var.melanostachys

Flavonoids: also important in black flowers

Benzene ring structure withside chains = UV absorbing

Morning glory

normal UV

Flavonoids appear dark to UV viewing insects – serve as nectar guides.

1.Anthocyanin flavonoids

• most important and widespread group of coloring matter in plants• found in almost all families of angiosperms• replaced by betalains in all families of a lineage of Caryophyllales (except Caryophyllaceae + Molluginaceae)

Carnation (Caryophyllaceae)anthocyanin

Ice plant (Aizoaceae), betalain

ANTHOCYANINS

Sarcodes sanguinea (snow plant), Ericaceae

2. Anthoxanthins (Yellow flavonoids)

• 20 families in distribution• give yellow color to flowers (in part); also found in leaves but masked• works in conjunction with yellow carotenoids -chemical mimicry

• black-eyed Susan - normal light

• - UV colorized

• - UV black/white: closer tohow UV-sensitive insects viewin this range of spectrum - bull’seye

yellow flavonoids

yellow carotenoids

2. Anthoxanthins (Yellow flavonoids)

2. Anthoxanthins (yellow flavonoids) in Gesneriaceae (African violets)Example: relationships within Gesneriaceae (African violet family) Subfamily Gesnerioideae Neotropical distribution Epigynous flowers Yellow flavonoids + carotenoids Subfamily Cyrtandroideae

Paleotropical distribution Hypogynous flowers Carotenoids only

2. Yellow flavonoids - utility in classification of Gesneriaceae

TAXA

Ovary position

Distribution Pigments

Subfam. Gesnerioideae

inferior New World Yellow flavonoids+ carotenoids

Subfam. Cyrtandroideae

superior Old World Carotenoids only

Columnea superior New World Yellow flavonoids + carotenoids

Biogeography, not gynoecium, consistent with chemical signal

Saintpaulia (African violet)

3. Colorless flavonoids - systematic utility: helps in the expression of anthocyanins

Sources of anthocyanins:

1.African violet flowers; Geranium flowers2.Leaves of Coleus, Begonia, red cabbage and red lettuce3.Fruits of cranberry, raspberry, strawberry and plum

4. Betalains - named after Beta (beet); structurally different from flavonoids, N-containing.

• found only in families of Caryophyllales (beets, cacti, pokeweeds, amaranths)

• anthocyanins and not betalain found in Caryophyllaceae + Molluginaceae

Mollugo verticillata Dianthus

deltoides

Families of Caryophyllales that contain betalains

Aizoaceae Amaranthaceae Basellaceae Cactaceae Chenopodiaceae Nyctaginaceae Portulacaceae

EchinocereusOpuntia

Lampranthus (ice plant) Aizoaceae

Red, violet

Yellow, orange

BETALAINS

Volatiles CompoundsVolatile compounds often restricted to families, genera, oreven species – parsley, sage, Rosemary, thyme. Animals, in turn, are attracted or repulsed by the odors

Parsley, Apiaceae

thyme

sage

rosemary

LAMIACEAE

Classical taxonomists used plant odors consciously or unconsciously in classifying plants into groups.Pinaceae - conifersLamiaceae - mintsApiaceae - carrots

Linnaeus’ “Sensual System” of classification1. Aromatic2. Fragrant3. Musk-like4. Garlic-like5. Goat-like6. Foul7. Nauseating

Camellia - fragrantAmorphophallus

Six major volatile groups1. Terpenes - pinenes.menthol, catnip2. Aliphatic oils - Magnolia,amyl acetate3. Aromatics - wintergreen4. Aminoid (N) - offensive,Aristolochiaceae, Araceae5. Sulphides (S) - onions6. Glucosinolates (S) - mustard

Aliphatic oil pheromone in orchids

SulphidesGlucosinolates

Nepeta (catnip or catmint), Lamiaceae

Amorphophallus titanum

TERPENESAMINOID

Aristolochia elegans

Glucosinolates (mustard oil glucosides)- useful in the classif of Capparales

Old schemes: Cruciferae, Capparaceae, Papaveraceae, and Fumariaceae grouped under Rhoeadales.

New schemes: Capparales: Cruciferae and Capparaceae

Papaverales: Papaveraceae and Fumariaceae

(alkaloid-containing)

Cleome spinosa

Dicentra formosa

MUSTARD OIL EVOLUTION

Systematic issue: 15 different looking families share mustard oils - are they related?

Limitation of flavonoids

Placement of Psilotum as the most primitive fern ally

Psilotum has biflavonyls, just like lycopods and gymnosperms

TERPENOIDS

Limited distribution Complex instrumentation and

experience

Sesquiterpene lactones

Certain groups in Compositae exhibit distinct types of STL

Phytogeography of Vernonia (tribe Vernonieae): 2 major centers of distribution, Neotropics and Africa

Stevia rebaudiana