Multiple authors (2006) Flora of Somalia 3: 465 - 558

Plants usually herbs or shrubs, sometimes small trees. Leaves usually alternate, sometimes opposite, sometimes varying along a stem, simple or dissected, not compound. Inflorescences capituluaof 1-many flowers (florets) sessile on a receptacle and surrounded by an involucre of specialized bracts, phyllaries; capitula solitary or variously arranged in secondary inflorescences [synflorescences but on this site,as is customary, called inflorescences), homogamous (all florets sexually alike) or heterogamous (florets sexually diverse); radiate  (with marginal florets having a corolla elongated on one side and radially symmetric central florets), discoid (all florets radially symmetric and alike), disciform (with 2 different kinds of radially symmetric florets), or ligulate (all florets with an elongated, strap-shaped, 5-toothed corolla. Florets sessileor subsessile on the common receptacle, bisexual, unisexual, or sterile; calyces represented by a pappus of awns, scales, bristles or hairs or a more or less crown-like cup-shpedor ear-shaped structure, or no pappus present. Corollas of (3-)5 united petals, varying from radially symmetric and equally to somewhat unequally lobed to clearly bilaerally symmetric. Stamens 5, filaments attached to the corolla tube; anthers usually united around the style, introrse, rounded to sagittate at the base and at the top. Ovaries inferior, with 1 seed; style 1, divided into 2 branches near the tip, stigmatic on their inner surfaces, branch tipes rounded to variously extended or appendaged. Fruits 1-celled, 1-seeded, indehiscent, usually an achene, rarely a drupe. sometimes crowned by the persistent pappus, endosperm vestigial or absent.

Asteraceae consitute the largest family of flowering plants. It is cosmopolitan in its distribution, being known from all parts of the world other than Antarctica. It includes about 1,600 genea and 25,000 species. 

©Trustees of the Royal Botanic Gardens, Kew; reproduced with permission. 

Key to genera in Somaliland and Somalia

Plants annual, biennial or perennial herbs, sometimes shrubs, rarely trees, with or without milky latex, sometimes armed with spines. Leaves alternate, opposite or rosulate, exstipulate, entire, toothed, lobed or variously dissected. Inflorescences of (2)5-many individual sessile flowers (florets) aggregated on a receptacle and surrounded by an involucre composed of 1-several series of bracts (phyllaries or involucral bracts), the whole structure termed a head or  capitulum; phyllaries herbaceous, scarious throughout or only on the margins, or chartaceous, usually with a sclerified portion in the centre; receptacles naked (epaleate) or bearing scales (paleate), long hairs or bristles, receptacular surface smooth, pitted, or with scale like ridges;; flowers in a head  heterogramous, the outer flowers ofter pitiallate and the inner bisexual,, or homogamous, either unisexual or all flowers bisexual; heterogamous heads radiate or discoid, homogamous heards discoid or ligulate.  Flowers epigynous, bisexual, fpisstillate or staminate (at least functionally) or sterile  Calyx often represented by a pappus of 1 or more series of bristles or scales on the apex of the ovary or sometimes pappus completely absent. Corolla gamopetalous, tubular, filiform, ligulate or rarely bilabiate, usually 3 or 5-toothed, rarely absent. Stamens 5, epipetalous, anthers connate forming a tube round the style, filaments free, rarely anthers free, dehiscence introrse, calcarate or ecalcarate, caudate or ecaudate or sometimes sagittate, endothecial tissues polar or radial; filaments usually with a collar. Ovary inferior, 1-celled. Style usually divided above into two branches with acute or obtuse sweeping hairs reaching below the furcation or not. Fruit cypsela, with or without ribs, sometimes with distinct carpopodium (basal attachment area).

Global distribution of the Asteraceae