Diversity And Classification of
Flowering Plants:
Eudicots: Asterids
Michael G. Simpson
Asterids
• Very large, diverse group
• 10 orders, many families
• Putative apomorphies:
– iridoid compounds
– sympetalous corolla
– ovules: unitegmic (one integument),
tenuinucellate (megasporangium 1-cell thick)
Ovules unitegmic, tenuinucellate
Apiaceae (=Umbelliferae) - Carrot family
(Apium, used in Pliny for a celery-like plant). 446 genera / 3,540 spp.
The Apiaceae are distinctive in being herbs, with
sheathing leaves, (compound or simple. often
decompound), the inflorescence usually an
involucrate compound umbel [rarely a head, simple
umbel, or reduced] with actinomorphic flowers
having a 2-carpellate and 2-loculate, inferior ovary,
each carpel with one, axile-apical, pendulous ovule,
the fruit a schizocarp of mericarps.
K 5 or 0 C 5 [0] A 5 G (2), inferior,
hypanthium absent.
Economically important members include a
number of food, herb, and spice plants, such as
Anethum, dill; Apium, celery; Carum, caraway;
Coriandrum, coriander; Cuminum, cumin;
Daucus, carrot; Foeniculum, fennel; and
Petroselinum, parsely; some species are
poisonous, such as Conium maculatum, poisonhemlock; others are used as ornamental cultivars.
Leaves sheathing
Inflorescence an umbel, compound umbel, or head
ovary inferior
placentation
apical-axile
stylopodium
Fruit a schizocarp of
mericarps
Araliaceae - Ginseng family
(possibly from French Canadian Aralie). 47 genera / 1,325 species.
The Araliaceae are distinctive in being mostly
tropical trees, shrubs, lianas, or herbs with palmate
or pinnate (rarely simple, then usually divided)
leaves, an inflorescence of heads, umbels, or with
umbel units, the flowers with often reduced calyx,
apopetalous to sympetalous corolla, and a 1-∞carpellate inferior ovary with usually apical-axile
placentation, the fruit a berry, drupe, or schizocarp.
K 0-5 C 5 [3-12] A 5-10 [3-∞] G (2-5) [(-∞)],
inferior, rarely superior.
Asteraceae (Compositae)
Characteristics:
Vegetatively variable.
Inflorescence a head (capitulum): (usu.) many flowers
arising from a compound receptacle, subtended by
inflorescence bracts: involucral bracts or phyllaries,
collectively termed the involucre.
Calyx modified as pappus.
Stamens syngenesious.
K pappus C 5 A (5) G(2), inferior, 1 basal ovule
Fruit an achene.
Asteraceae (=Compositae) Sunflower family
(after Aster, meaning star). 1,528 genera / 22,750 species.
The Asteraceae are distinctive in being herbs, shrubs, vines, or
trees, the inflorescence a head (capitulum) subtended by an
involucre of phyllaries, flowers either bilabiate, disk, or
ray/ligulate, (heads of many taxa a mixture of central disk
flowers and peripheral ray flowers), with the calyx, termed a
pappus, modified as scales, awns, or capillary bristles (or
absent), the androecium syngenesious, and with an inferior
ovary with a single, basal ovule, the fruit a multiple of achenes.
Asteraceae (=Compositae) Sunflower family
(after Aster, meaning star). 1,528 genera / 22,750 species.
Economic importance includes some food plants
(e.g., Cynara scolymus, artichoke, and
Helianthus annuus, sunflower), a number of
ornamental cultivars, and various species used
locally or industrially; the prickly fruits of
Arctium lappa (burdock) are purported to have
been the model for invention of velcro.
Argyroxiphium sandwicense, Silversword
Maui
Argyroxiphium sandwicense, Silversword
Maui
Asteraceae (=Compositae) Sunflower family
(after Aster, meaning star). 1,528 genera / 22,750 species.
K 0-∞ (pappus)
C (5) [(4)] or (3) in some ray flowers
A (5) [(4)]
G (2), inferior, hypanthium absent.
Asteraceae: floral variation
Three types of flowers:
1) Bilabiate: zygomorphic (bilateral) with 2 lips
2) Ray (ligulate): zygomorphic (bilateral) with 1
lobe
3) Disk: actinomorphic (radial), usu. 5-lobed
Five types of heads:
1) discoid, with only disk flowers;
2) disciform, with central disk flowers and
marginal, eligulate female flowers;
3) radiate, with central (bisexual or male) disk
flowers and peripheral (female or sterile) ray
flowers;
4) ligulate, with all ray flowers (typically with
5-toothed corolla apices);
5) bilabiate, with all bilabiate flowers.
Bilabiate flower
posterior lip
anterior lip
Acourtia microcephala
Trixis californica
disk
ligulate / ray
anthers
connate
syngenesious
Ray flowers (heads ligulate = all rays)
ligulate corolla
Rafinesquia neomexicana
Malacothrix californica
Disk flower: heads discoid
disk corolla
Chaenactis gabriuscula
Palafoxia arida
Psathyrotes ramosissima
Disk flowers: heads disciform
(2 types of disk fls.,
same or different heads)
male heads
female heads
Ambrosia chamissonis
Heads radiate: inner disk & outer ray fls.
disk flowers
ray flowers
Encelia farinosa
Xylorhiza orcuttii
Some heads are "chaffy"
ovary
disk flower
chaff :
bracts
subtending
flowers
Encelia californica
Involucre morphology
one whorl
two whorls
Senecio vulgaris
Coreopsis maritima
many whorls
Encelia californica
Involucre morphology
Phyllaries spiny
Phyllaries spiny & squarrose
Circium vulgare
Silybum marianum
Pappus:
modified calyx
beak
capillary bristles,
borne atop "beak"
capillary bristles:
barbellate
capillary bristles:
plumose
Pappus: modified calyx