COMPOSITAE Giseke (ASTERACEAE Bercht. & J. Presl)
This is the largest family of vascular plants of the Palaearctic and one of the largest in the world, as it consists of some 1,910 genera and about 32,900 species. It consists mainly of herbaceous species, rarely trees, shrubs and lianas. It is distributed around the world, from the Arctic mountains to tropical rainforests. What all species have in common is their flowers, arranged in capitula surrounded by an involucre of bracts, with a ± enlarged, flat or convex receptacle on which flowers are inserted, which can be alveolate and have hairs or scales between the flowers. Flowers may be unisexual or hermaphrodite, and the North African species there are of 2 types: ligulate and ray florets, both zygomorphic, with petals fused in a short tube at the lower part and the rest in the shape of a tongue with 5 lobes (true ligulate flowers) or 3 lobes (ray florets), or actinomorphic flowers with a tubular corolla with 5 apical lobes (disc florets). The androecium consists of 5 stamens, free at the filaments, but with coalescent anthers forming a ± long exserted tube surrounding the style. The ovary is always inferior and the calyx absent or transformed into a pappus formed by hairs, scales or a membranous corona. The fruit is a cypsela (achene produced by an inferior ovary).
In North Africa, this family is composed of 124 species, the vast majority herbaceous. The species of the genera Pluchea and Warionia can become arborescent, but in general all the woody species are small shrubs or subshrubs. All genera with woody species, whether shrubs or subshrubs with more of 50 cm, have been included in the following key.
Key to genera
1 Capitula with all flowers ligulate. Plants with latex 2
1 Capitula with all flowers in disc florets, or flowers with disc florets and with ligulate or ray florets. Plants without latex 4
2 Cauline leaves with longly decurrent base on stem. Capitula with 4(5) flowers Lactuca
2 Cauline leaves with base not decurrent. Capitula with 6 or more flowers 3
3 Achenes cylindrical or slightly compressed. Capitula with 6-20(25) flowers Launaea
3 Achenes clearly compressed. Capitula with more than 20 flowers Sonchus
4 Capitula with only disc florets 5
4 Capitula with ligulate or ray florets in the periphery and disc florets in the centre 20
5 Leaves with spines 6
5 Leaves without spines 7
6 Capitula surrounded by involucral leaves similar to cauline leaves and longer than the involucre. Receptacle hairy Carthamus
6 Capitula not surrounded by involucral leaves similar to cauline leaves. Receptacle hairless Iphiona
7 Cactiform shrub, with thick cylindrical stems. Involucre with an internal row of long bracts and an outer row of very short bracts Kleinia
7 Shrub or subshrub not cactiform. Involucre with several rows of imbricate bracts 8
8 Capitula 3-12 mm long, grouped in dense spiciform, paniculate or corymbose inflorescences 9
8 Capitula (5)8-40 mm long, solitary or grouped in lax corymbose inflorescences 12
9 Achenes without pappus 10
9 Achenes with pappus 11
10 Receptacle with interfloral scales. Capitula 6-9 mm in diameter Achillea pp
10 Receptacle without interfloral scales. Capitula 1.5-6 mm in diameter Artemisia
11 Leaves entire. Involucral bracts with entire margin Helichrysum
11 Leaves dentate. Involucral bracts with fimbriate margin Pluchea
12 Achenes without pappus, or pappus formed by a membranous liguliform corona 13
12 Achenes with pappus formed by scabrid or feathery hairs 14
13 Achenes without pappus Santolina
13 Achenes with pappus formed by a membranous liguliform corona Pentzia
14 Pappus formed by feathery hairs Ptilostemon
14 Pappus formed by hairs or scabrid scales 15
15 Involucral bracts with pectinate apical appendage or with a well developed apical spine. Flowers blue-violet, pinkish or reddish 16
15 Involucral bracts without pectinate apical appendage, obtuse, acute or acuminate, but without a well developed apical spine. Flowers yellow, sometimes with purple lobe apices 17
16 Involucral middle bracts with apical spine (1.5)12-15 mm. Receptacle with setaceous interfloral scales Centaurea
16 Involucral middle bracts unarmed. Receptacle hairy Cheirolophus
17 Capitula 30-40 cm long. Leaves sinuate-pinnatifid Warionia
17 Capitula 6-25 mm long. Entire or toothed leaves 18
18 Capitula with involucral leaves similar to cauline leaves and longer than the involucre Perralderia pp
18 Capitula without involucral leaves 19
19 Achenes not compressed. Capitula with peripheral flowers filiform and feminine and other flowers in disc florets and hermaphrodite. Involucral bracts with scarious margin and apex Phagnalon
19 Achenes compressed. Capitula with all flowers in disc florets and hermaphrodite. Involucral bracts, at least the outer bracts, without scarious margin Chiliadenus
20 Involucre with a single row of bracts. Leaves fleshy Hertia
20 Involucre with 2 or more rows of bracts. Leaves herbaceous or fleshy 21
21 Involucre with interfloral scales 22
21 Involucre without interfloral scales 27
22 Capitula with involucral leaves similar to cauline leaves and longer than the involucre 23
22 Capitula without involucral leaves 26
23 Leaves pinnatisect Cladanthus
23 Leaves entire, dentate or sinuate-lobulate 24
24 Achenes without pappus Anvillea
24 Achenes with pappus formed by short scarious scales 25
25 Achenes of ray florets highly compressed; those of the disc florets slightly compressed Pallenis
25 Achenes of ray florets triquetrous or slightly compressed; those of disc florets cylindrical Asteriscus
26 External achenes without pappus; internal achenes with pappus formed by 3-5 setae with feathery apex Rhanterium
26 All achenes without pappus Achillea pp
27 Capitula with involucral leaves similar to cauline leaves and longer than the involucre Perralderia pp
27 Capitula with involucral leaves 28
28 Pappus formed by long scabrid setae surrounded by an outer row of short scales ± fused together Pulicaria
28 Pappus formed by long scabrid setae; without short scales 29
29 Plants glabrous. Leaves fleshy, linear, entire or with tridentate apex. Hairs of pappus not fused together Limbarda
29 Plants hairy-glandular. Leaves herbaceous, lanceolate. Hairs of pappus fused together at the base Dittrichia
Updated by: B. Valdés & J. Charco.