1528 genera, 22,750 spp., worldwide; mainly herbaceous, but some are woody. Flowers in dense, pseudanthial heads (capitula), the common receptacle of these surrounded by an involucre of bracts; bisexual, or some female, sterile, or functionally male. Flowers epigynous and all tubular and regular, or just the central ones (disk flowers), the marginal ones (ray flowers) irregular with strap-like (ligulate) corollas, or all flowers with either ligulate or bilabiate corollas.
Judd et al. 1999, pp. 396-401.
A synapomorphy for the Asteraceae (excluding the Barnadesieae) is a 22 kb inversion in the chloroplast genome (shown in color; LSC, large single-copy region; SSC, small single-copy region; IR, inverted repeat; trnX, tRNA genes).
Rudbeckia hirta (Heliantheae) is illustrated below as an example of some of the morphological features that characterize the family (Br, floral bract; G, inferior ovary; C, tip of corolla tube; A, tip of staminal tube; St, lobe of stigma; at right, the staminal tube split and unrolled - note the free filaments).
|K (pappus) developing only on fruit or absent, of hairs, bristles, awns, or scales. C(5). A5, inserted on C, filaments usually free but anthers united in a ring (syngenesious). G(2), with a single locule containing a single ovule. The fruit is an achene-like cypsela1.|
Disk flowers with tubular C, hermaphrodite or male.
Ray (marginal) flowers with ligulate C, sterile or female.
Flowers with bilabiate (2+3, 4+1) C also formed.
Heterogamous capitula with both disk and ray flowers; homogamous capitula with exclusively one or the other.
Capitula can usefully be classified further by referring to the morphology of the flowers they contain, as has been done in the ROM Field Guide to Wildflowers... (p. 144), namely as
Ontario native and naturalized genera of Asteraceae include the following: Arctium, Bidens, Cichorium, Galinsoga, Helianthus (also illustrated above), Rudbeckia, Silphium, Solidago, Symphyotrichum (=Aster), Taraxacum, and Tragopogon. Lactuca sativa is lettuce.
|1. Cypsela - a single-seeded, dry, indehiscent fruit that develops from an inferior ovary that in turn developed from two gynoecial primordia (hence the two branches of the stigma in the flower). It is achene-like in that the ovary wall is not joined to the seed coat of the enclosed seed.|
Tribal classification after Mabberley (1997, 2008); compare with Judd et al. (2008; Table 9.4 - note synapomorphies for tribes) and Zomlefer (1994; Table 14, pp. 206-207) especially for additional distinguishing characteristics (in parentheses, subfamilies I, Barnadesioideae; II, Cichorioideae; III, Asteroideae).
|Anthemidae (III)||108/1725, cosmop.||herbs, some shrubs||heterogamous||K none, or ring or cup; C tubular or tubular/ligulate|
|Arctotideae (II)||18/200, warm, esp. S Africa||herbs, shrubs||heterogamous||K none, or not capillary; C usually tubular and ligulate|
|Astereae (III)||178/2700, cosmop.||herbs, shrubs, some trees||heterogamous||K various, C tubular or tubular/ligulate|
|Barnedesieae (I)||9/92, S. America||shrubs, small trees or herbs (97% woody)||homo- or heterogamous||K bristles with long hairs; C tubular or ligulate|
|Calenduleae (III)||8/85, Africa, SW Asia, Europe||herbs, shrubs||heterogamous||K none, C tubular/ligulate|
|Cardueae (II)||79/2500, mostly Eurasia||herbs, one pachycaul tree||homogamous (or with sterile outer flowers)||K capillary, C tubular|
|Eupatorieae (III)||169/2400, mostly New World||herbs, shrubs||homogamous||K 5-many bristles or scales, or none; C tubular|
|Gnaphalieae (III)||183/2050, cosmopolitan, esp. S. Afr., Australia||herbs, shrubs, or shrublets (often ericoid)||homogamous (mostly)||K usually capillary bristles, C tubular (rarely tubular/ligulate)|
|Helenieae (III)||93/635, America, esp. N.; few Old World||herbs, trees in one genus||heterogamous|
|Heliantheae (III)||196/2500, cosmop., esp. America||herbs, shrubs, trees, lianes||heterogamous||K usually 2-3 awns or scales, C tubular or tubular/ligulate; NB black anthers|
|Inuleae (III)||38/480, Old World, esp. Eurasia||perennial herbs, shrubs, tree||heterogamous||K scales or capillary bristles, C tubular/ligulate|
|Lactuceae (II)||97/1530, cosmop., esp. N. hemisphere||herbs, some pachycaul trees; produce latex||homogamous||K simple or plumose, C ligulate|
|Liabeae (II)||14/160, tropical New World||shrubs or trees||homo- or heterogamous||K usually capillary bristles, C tubular or tubular/ligulate|
|Mutiseae (II)||77/950, warm||herbs, lianes, trees||homo- or heterogamous||K capillary, C variable, bilabiate (2+3) or ligulate|
|Plucheeae (III)||28/180, trop. and warm, incl. arid||herbs, shrubs, trees||homo- or heterogamous||K scales or capillary bristles, C tubular|
|Senecioneae (III)||119/3225, cosmop.||herbs, shrubs, trees, lianes||homo- or heterogamous||K capillary, C tubular or tubular/ligulate|
|Vernonieae (II)||98/1530, mostly tropical||herbs, shrubs, trees||homogamous||K setose, C tubular (rarely ligulate)|
See content from The International Compositae Alliance's new book, Systematics, Evolution, and Biogeography of the Compositae (Funk, Susanna, Stuessy & Bayer 2009) HERE:
The Flora North America treatment of the Asteraceae (Barkley, Brouillet & Strother 2006) is available HERE:
L. Watson and M. J. Dallwitz
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