Neotropical Compositae (Asteraceae)

D.J. Nicholas Hind

Royal Botanic Gardens, Kew, UK. 

Description

Habits: annual or perennial herbs, subshrubs or shrubs, climbers, lianes or ramblers, small or, rarely, large trees, epiphytes, very rarely true aquatics, glabrous or with simple, glandular, malpighiaceous or stellate hairs, often glabrescent; plants usually monoecious, rarely dioecious, odourless or rarely with distinctive odour. Rootstocks fibrous or fleshy, sometimes with distinct woody perennating rootstocks (xylopodia). Stems usually unarmed, rarely spinyLeaves alternate or opposite, sometimes rosulate, rarely whorled, estipulate, lamina simple, rarely compound, variously shaped, pinnately or palmately veined, usually herbaceous, sometimes fleshy, coriaceous, or chartaceous, sessile or petiolate, sometimes with an expanded, sheathing or auriculate base but never stipulate, margins lobed or variously toothed, rarely spiny and rarely ending in a tendril, and rarely reduced to scales and falling rapidly. Primary inflorescence a capitulum, usually chasmogamous, very rarely cleistogamous, usually of many small individual flowers (florets), sometimes reduced to 1, surrounded by an involucre of protective bracts (phyllaries) in one or more series, cylindrical, to globular or urceolate; phyllaries imbricate, subimbricate or distant, usually gradate or sometimes subequal, rarely outer longer than inner, usually homomorphic, very rarely heteromorphic, often chartaceous or herbaceous, sometimes with characteristic apical appendages, rarely with an outer series of subinvolucral bracts forming a calyculus; receptacle solid or hollow, concave, flat or convex, rarely conical or almost cylindrical, surface plane, variously ornamented and areolate, alveolate or fimbriate around achene attachment points, commonly naked but sometimes with chaffy bracts (paleae), scales, bristles or hairs between florets. Inflorescence of capitula usually cymosely arranged within flowering structure but also in corymbose panicles, or rarely spicate, sometimes scapiform, rarely secondarily aggregated into spikes or glomerules, or very rarely arranged in compound structures or synflorescences (syncalathia) possessing a secondary receptacle, rarely also with a secondary involucre, sometimes each individual capitulum within compound structure reduced to single-flowered condition. Capitula homogamous and all florets hermaphrodite or more rarely all male (staminate) or all female (pistillate), very rarely unisexual capitula borne on same plant or on different plants, capitula discoid (with all florets tubular and actinomorphic), ligulate (with all florets ligulate), or bilabiate (with all florets bilabiate), and all florets hermaphrodite, all male, or all female, or capitula heterogamous and radiate with outer marginal florets female (pistillate), or sterile or neuter, and radiate in one or more whorls, and inner disc florets usually hermaphrodite with tubular corollas, or heterogamous and disciform (possessing at least 2 types of eradiate florets, usually with filiform outer florets and central tubular hermaphrodite florets), or heterogamous and radiant (possessing inner hermaphrodite florets and outer enlarged, usually sterile or neuter marginal florets). Florets few, very rarely 1, to many, arranged racemosely or indeterminately within capitula, outer opening first; corollas variously coloured, actinomorphic and typically in disk florets in radiate, or throughout discoid, capitula, or with zygomorphic corollas and bilabiate (with a 3-toothed outer lip and 2-lobed inner lip), pseudobilabiate (with a 4-toothed outer lip and a 1-lobed inner lip), rayed (lacking adaxial lobes but with a limb with 1 to 4 apical teeth), or ligulate (with a flat, strap-shaped limb with 5 apical teeth), glabrous or variously pubescent (eglandular or glandular), corolla lobes short or long, glabrous or variously pubescent, often with thickened apical margin; anthers typically connate (exceedingly rarely anthers free), usually 5 (rarely 4) forming a tube around the style, and dehiscing introrsely, dorsifixed or basifixed, conspicuously exserted from, or included within corolla throat, apical anther appendages (diagnostic in many genera in Eupatorieae) acuminate, apiculate, acute, obtuse, usually persistent, basal anther appendages calcarate and caudate, rarely ecalcarate, tails long or short, entire or variously laciniate, rarely branched or pilose; filaments inserted basally inside corolla tube, higher up in tube or just beneath sinuses of corolla-lobes, usually glabrous, rarely papillose or even hairy, very rarely filaments fused together, filaments often with a conspicuous (and diagnostic) anther or filament collar just below insertion point on anther; styles often well exserted from corolla throat and anther cylinder, usually divided into 2 style arms (rarely connate) each with stigmatic surface on inner surface, style hairy, hairs acute or obtuse to rounded, papillose or glabrous, sometimes with distinctive (and diagnostic) basal node, with or without a nectary, glabrous or pubescent; style arms sometimes with characteristic sterile apical appendages, stigmatic papillae often conspicuous and arranged along style arm margins or inner surfaces or inconspicuous and either marginal or all over inner surfaces. Fruit single-seeded, indehiscent, lacking endosperm, developing from an inferior ovary (a cypsela, although commonly termed an achene), obovoid or oblong, fusiform or distinctly beaked, terete, angular, rounded, variously compressed or curved, ribbed, angled, variously ornamented or winged, glabrous or variously pubescent (frequently with diagnostic eglandular duplex, or twin-hairs) or glandular, rarely myxogenic, with or without phytomelanin in achene body walls; carpopodium (basal attachment area to receptacle) usually present (diagnostic in some genera) and of several layers of variously enlarged, sometimes ornamented cells, usually delimited from body of achene in form or colour, usually symmetrical, rarely eccentric, variously annular, cylindrical, or stopper-shaped, sometimes procurrent on base of achene, usually glabrous, rarely replaced by an elaiosome; apically usually possessing a pappus (considered a modified calyx) of uniseriate to few- or multi-seriate smooth, barbellate or plumose fine hairs, bristles, scales, or awns (sometimes more or less fused together), usually separate, rarely basally connate, caducous, deciduous or persistent, rarely a laciniate crown, sometimes completely lacking.

 

Diagnostic descriptions of the Tribes of the Compositae

Tribe: 1. Barnadesieae
Habits
: shrubs or trees. Stems often with axillary spines. Leaves alternate, apex mucronate or spiny. Capitula usually homogamous and discoid, rarely heterogamous and disciform; phyllaries imbricate, multiseriate; receptacle paleaceous or epaleaceous. Corollas actinomorphic or slightly zygomorphic or bilabiate, throat pubescent inside, corolla-lobes long, erect, ascending or recurved, densely long pubescent towards apices; flower colour yellow, white red or violet; anther-bases short-sagittate or conspicuously tailed; style arms short, obtuse. Achenes usually brown; pappus of uniseriate plumose hairs.

Tribe 2. Mutisieae
Habits
: herbs, shrubs or trees. Stems unarmed. Leaves alternate, usually unarmed, rarely apically spiny. Capitula radiate, subradiate or discoid, homogamous or heterogamous; phyllaries usually imbricate, multiseriate; receptacle usually naked. Corollas often bilabiate, sometimes regular or ligulate; corolla-lobes long; flower colour white, yellow; anther-bases often conspicuously tailed; style arms short obtuse, or truncate and fringed. Achenes usually brown; pappus usually of simple hairs, rarely plumose.

Tribe: 3. Cardueae
Habits
: herbs or rarely shrubs. Leaves alternate, often thistle-like. Capitula homogamous, discoid or radiant; phyllaries imbricate, multiseriate, often spiny or appendaged; receptacle usually densely bristly or fimbriate. Florets purple, white or yellow. Corollas regular; corolla-lobes long; anther-bases tailed; style arms usually obtuse, short and with a thickened often hairy zone below them. Achenes not black; pappus usually of hairs, sometimes plumose, or of scales.

Tribe: 4. Lactuceae
Habits
: herbs or shrubs with milky juice present in tissues. Leaves alternate. Capitula ligulate, homogamous; phyllaries imbricate, 1-several-seriate; receptacle naked or scaly. Florets yellow or purple. Corollas all ligulate, apically 5-toothed, corolla-lobes long; anther-bases acute; style arms slender, tapered or obtuse. Achenes not black; pappus usually of hairs, sometimes plumose.

Tribe: 5. Vernonieae
Habits: shrubs or herbs. Leaves usually alternate, sometimes opposite. Capitula homogamous, discoid; phyllaries imbricate, multiseriate; receptacle usually naked. Corollas regular; corolla-lobes long; flower colour purple, sometimes white, rarely yellow; anther-bases acute, sagittate; style arms long, narrow, pointed, hairy. Achenes not black; pappus usually of hairs, sometimes paleaceous and of two distinct series.

Tribe: 6. Liabeae
Habits
: shrubs or climbers. Leaves opposite, often whitish beneath. Capitula usually radiate; phyllaries imbricate in several series; receptacle usually naked. Florets yellow. Corollas regular or outer radiate; corolla-lobes long; anther-bases sagittate, sometimes fringed; style arms narrow, pointed, hairy. Achenes not black; pappus usually of hairs.

Tribe: 7. Arctotideae
Habits
: herbs or rarely shrubs. Leaves alternate, often thistle-like and white beneath. Capitula usually radiate; phyllaries imbricate, multiseriate, often spiny or membranous; receptacle often alveolate, with fringed pits, rarely scaly. Florets yellow. Corollas regular, usually radiate; corolla-lobes long; anther-bases usually not tailed, more or less sagittate; style arms usually obtuse, short and with a thickened often hairy zone below. Achenes not black; pappus usually of scales. [Not native to the Neotropikey area].

Tribe: 8 Inuleae
Habits
: shrubs or herbs. Leaves alternate, sometimes decurrent on the stems. Capitula radiate, disciform and doughnut-like with inner bisexual and narrow outer female corollas, or discoid; phyllaries imbricate in several series, often papery and white or coloured in upper part; receptacle naked or scaly; corolla-lobes short; flower colour disc yellow, rays usually yellow, rarely purplish; anther-bases finely tailed; style arms unappendaged, rounded or truncate and fringed. Achenes not black; pappus usually of hairs.

Tribe: 9. Calenduleae
Habits
: herbs or rarely shrubs. Leaves alternate, rarely opposite. Capitula radiate; phyllaries 1-3-seriate; receptacle naked. Florets yellow, orange or purple; corolla-lobes short; anther-bases sagittate, more or less tailed; style arms more or less obtuse. Achenes not black, large, often irregular or winged, or if black then fleshy, sometimes heteromorphic; pappus absent. [Only represented by cultivated, sometimes escaped, Calendula officinalis].

Tribe: 10 Astereae
Habits
: subshrubs, shrubs or herbs, rarely small trees. Leaves alternate. Capitula radiate, disciform and doughnut-like with inner bisexual and narrow outer female corollas, or discoid; phyllaries imbricate, 2-multi-seriate; receptacle naked, rarely glandular; corolla-lobes short; floret colour disc yellow, rays commonly purplish, bluish or white, sometimes yellow; anther-bases usually obtuse, not tailed; style arms flattened, with hairy apical triangular to subulate appendages. Achenes not black, often flattened with 2 marginal veins; pappus often of hairs, sometimes reduced, coroniform or absent.

Tribe: 11. Anthemideae
Habits
: annual or perennial herbs or shrubs. Leaves alternate, rarely opposite, often much divided and strongly aromatic. Capitula radiate, disciform or discoid; phyllaries imbricate, 2-multi-seriate, with dry often brownish membranous or scarious margins; receptacle naked or scaly. Florets disc yellow, rays yellow or white; corolla-lobes short; anther-bases obtuse; style arms obtuse to truncate, unappendaged. Achenes not black; pappus not of bristles, usually cup-like, ear-shaped, or crown -like, or absent, rarely of scales.

Tribe: 12 Senecioneae
Habits
: shrubs or herbs. Leaves alternate. Capitula radiate or discoid, rarely disciform; phyllaries usually uniseriate only, with or without a few much shorter outer ones; receptacle naked; corolla-lobes usually short; flower colour yellow or purplish, blue or white; anther-bases obtuse to sagittate, rarely tailed; style arms truncate and fringed or appendaged. Achenes not black; pappus usually of hairs.

Tribe: 13. Heliantheae
Habits
: herbs, or shrubs, rarely tree -like. Leaves often opposite, sometimes alternate, pubescent often rather rough and scabrid, rarely glabrous or glabrescent. Capitula often radiate, sometimes disciform or discoid rays usually broad; phyllaries 1-2-multi-seriate, when uniseriate often conspicuously gland-dotted; receptacle often scaly, sometimes naked; corolla-lobes short; flower colour usually yellow, sometimes purple, disc sometimes dark-coloured; anther-bases more or less obtuse; style arms truncate or appendiculate. Achenes usually black with phytomelanin in walls; pappus usually of awns or scales, sometimes absent, rarely of hairs, sometimes plumose.

Tribe: 14. Eupatorieae
Habits
: herbs, shrubs, climbers, rarely trees. Leaves usually opposite, sometimes whorled, sometimes alternate. Capitula homogamous, discoid; phyllaries imbricate, 2-multi-seriate; receptacle usually naked. Corollas regular; corolla-lobes short; flower colour purple, blue or white, never yellow; anther-bases obtuse; style arms obtuse, more or less club-shaped, often very conspicuous and long-exserted. Achenes black with phytomelanin in walls; pappus usually of hairs.

Notes on delimitation

  • This is one of the 'natural' families, and as such there is no problem in delimiting the family, since all members can be properly attributed to it with careful examination.
  • The number of subfamilies in the Compositae has risen to over a dozen (and likely to rise still further), with the somewhat impractical expansion of the number of tribes to 30. From a purely practical point of view, in terms of teaching and fieldwork, there is little wrong in recognizing the tribes as proposed by Bentham (1873), but recognizing a separate Barnadesieae and Liabeae, and combining the Helenieae within a broader circumscription of the Heliantheae.
  • Within the Neotropics I currently recognize 13 tribes as possessing native or naturalized species; only the tribe Arctotideae is absent although some species may well be cultivated.
  • A key to the tribes found in the Neotropics is provided below, together with diagnostic/conspectus-like descriptions of each of the tribes above.

Distribution in the Neotropics

  • Found throughout the Neotropics, although species numbers are restricted in rainforest and extensive aquatic habitats. The family is particularly common in montane habitats, disturbed areas and in semi-arid regions, and is common (as weeds) in most cultivated regions.

Distinguishing characters (always present)

  • The combined presence of diminutive flowers (termed florets) massed into a capitulum surrounded by protective involucral bracts (termed phyllaries) in one or more series.
  • Gamopetalous corolla.
  • A style with two apical style arms (usually, but not always, divided).
  • 5 anthers united into a cylinder around the style and dehiscing antrorsely.
  • Pappus of capillary setae or of scales (although sometimes absent).
  • Fruit an achene (or more correctly a cypsela).

Key differences from similar families

Close examination will place all members of the Compositae within the family without any great difficulty. However, superficial examination may well place some taxa, albeit very rarely, into other families. Both vegetative and fertile material of Ichthyothere is sometimes misplaced in the Commelinaceae. Material from other families is often placed in the Compositae, most notably members of the Acanthaceae, Amaranthaceae, Labiatae and sometimes Rubiaceae. All of these families are instantly thrown out because they have:

  • Free stamens.
  • Capitate stigmas.
  • Typically distinct calyces.
  • No pappus -like structure.
  • Very distinctive fruiting structures.

 

Allied families, such as the Calyceraceae and Goodeniaceae, and other families historically placed close to the Compositae, such as the Dipsacaceae and Valerianaceae, are similarly easy to distinguish upon close examination.

Number of genera

  • c. 1600 total for family globally; total as yet unknown in the Neotropics.

Useful tips for generic identification

  • It is especially important to make sure that fertile material is collected that shows all floret types open and ideally with mature achenes - although achene maturation will usually take place whilst material is being dried in the press.
  • In many genera pappus length varies considerably between flowering and fruiting material, as does achene shape and size (especially in those taxa developing beaked achenes), and often receptacular paleae grow (and can change colour) considerably in fruiting capitula.

 

Key to tribes of the Compositae (Asteraceae) in the Neotropics

1. Corolla inside and outside and all other floral parts bearing simple, uniseriate, eglandular, 3-celled hairs; plants often with axillary spines or thorns 1. Barnadesieae
1. Corollas and other floral parts lacking such hairs but often with hairs of other kinds, or glabrous; stems lacking spines or thorns, or if stems apparently spiny these formed from branch and branchlet apices 2

2.  Corollas all ligulate (i.e. all strap-shaped, equally 5-toothed at apex) 3
2.  Corollas not ligulate, or if strap-shaped then limb with 4 or less apical teeth, or teeth unequal 4

3.  Plants lacking latex; style arms lacking collector hairs 2. Mutisieae p.p. (Hyaloseris)
3.  Plants with latex; style arms subulate, pubescent outside and to below bifurcation on style shaft 6. Lactuceae

4.  Phyllaries uniseriate, usually cohering by overlapping margins, or partly or wholly connate, calyculate or ecalyculate; pappus present 5
4.  Phyllaries imbricate in 2 or more series, free or connate, if uniseriate then not cohering or pappus absent or capitula unisexual 6

5.  Plants with oil glands on leaves and phyllaries; achenes black when mature 12. Heliantheae p.p.
5.  Plants lacking oil glands; achenes never black when mature 7. Senecioneae p.p.

6.  Style arms bifurcate or short-bifid, pilose outside; upper part of style shaft pilose 7
6.  Style arms bifurcate or bilobed, rarely connate, not pilose outside; upper part of style glabrous or sometimes with a ring of hairs just beneath style arm division 9

7.  Florets isomorphic, all hermaphrodite; corolla tubular, usually long lobed 4. Vernonieae
7.  Florets dimorphic, outer florets female with filiform corollas or with rays, disc florets tubular, hermaphrodite or male; corolla lobes short 8

8.  Outer florets filiform; leaves alternate; plants never with latex 11. Inuleae p.p.
8.  Outer florets rayed; leaves opposite (rarely rosettiform); plants with or without latex 5. Liabeae

9.  Capitula with all or only outer florets bilabiate (i.e. corollas with 3-toothed outer lips and 2-lobed inner lips) 2. Mutisieae p.p.
9.  Capitula lacking bilabiate florets, corollas all tubular or outer florets distinctly rayed, ray limb not bilabiate 10

10.  Style with ring of hairs just beneath style arms 3. Cardueae
10.  Style arms lacking ring of hairs and glabrous or variously papillate or pubescent 11

11.  Anther bases not sagitate, base of thecae obtuse 12
11.  Anther bases conspicuously sagitate, thecae long-acute or acuminate 13

12.  Capitula with marginal filiform female florets; style arms truncate with a corona of hairs Inuleae p.p.
12.  Capitula with all florets tubular; style arms obtuse and lacking collector hairs 2. Mutisieae p.p.

13.  Style arms long, linear or apically clavate, covered in short papillae beginning conspicuously above base of style arms (florets isomorphic, all hermaphrodite, tubular; corollas never yellow) 13. Eupatorieae
13.  Style arms short, in upper part covered in collector hairs, rarely without collector hairs, or long [account for this if necessary] (florets isomorphic or dimorphic, hermaphrodite corollas usually yellow) 14

14.  Style arms truncate or obtuse 15
14.  Style arms subulate to triangular 17

15.  Pappus of capillary setae; involucre calyculate 7. Senecioneae p.p. (Culcitium)
15.  Pappus absent or a hyaline corona; involucre ecalyculate 16

16.  Phyllaries with scarious, usually brown margins; achenes relatively small, monomorphic or sometimes dimorphic, pappus a lacerate crown or auricle, or absent; leaves often pinnatipartite 10. Anthemideae
16.  Phyllaries green and herbaceous; achenes relatively large, polymorphic, epappose; leaves entire or lobed 8. Calenduleae (Calendula)

17.  Achene body never black, very frequently setuliferous, rarely glabrous; pappus usually of capillary barbellate setae, or absent, rarely of squamellae and then falling rapidly; leaves usually alternate, but never scabrid pubescent; receptacle usually epaleaceous 9. Astereae
17.  Achene body black, usually glabrous or sometimes setuliferous; pappus of scales, squamellae, aristae or awns, or absent, but never of capillary setae, or if setae present these plumose; leaves frequently opposite and scabrid pubescent; receptacle frequently paleaceous 12. Heliantheae

Notable genera and distinguishing features

  • Within the Neotropics there are very many notable genera, and certainly too many to separate out. In each ecostystem, within each of the countries in the area, there may well be dominant, or abundant, or otherwise noteworthy Compositae.
  • With the exception of the rainforest, and extensive aquatic habitats, the family is present in most of the ecosystems found in the area.

Status

  • In each of the main countries in the Flora area there are very high percentages of native taxa, and significant percentages of endemics. Many weedy taxa, from both New World and Old World, exist within the Flora area and there are many Neotropical taxa naturalized within others.

General notes

MINIMAL GLOSSARY OF TERMS USED WITHIN THE COMPOSITAE

NB. Because of the higher orders of arrangement found in the flowering structures of the family many terms have modified definitions.

Important literature

The literature on the Compositae is vast, although within the Flora area there are relatively few full (or state-based) floristic treatments for the family (Argentina - in progress, Guianas, Venezuela, Mexico - in progress, Santa Catarina, Brazil - in progress). Checklists exist for several countries (e.g. Argentina, Bolivia, Peru, Ecuador), but some floras are historical and considerably out of date (e.g. Brazil).

There are very few Flora Neotropica monographs available for any part of the family.

The Kubitzki volume of the Families and Genera of Vascular Plants on the Asterales, vol. VIII, covers the family, at tribal and generic level, comprehensively for the first time with keys to most taxa down to genera. Significant literature is listed at length in this volume.