Asteraceae Bercht. & J.Presl

Hind, D.J.N. (2009). Neotropical Asteraceae.

Morphology

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 spiny . Leaves 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

Distribution

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.

Diagnostic

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.

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.

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 hyalinecorona; 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

General Description

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.

• achene: a one-seeded fruit.
• antherappendage: usually refers to the apical appendages; basalanther -appendages are often highly characteristic at generic level.
• anther collar: a region of cells, often denoted by swelling, at apex of filament below anther, sometimes called a filament collar.
• awn: a stiff bristle-like pappus.
• barbellate: usually referring to pappus -setae where the branches of the seta are markedly shorter than the diameter of the seta.
• beak: referring to achene (Chaptalia, etc.) where the apex of the achene is elongated below the pappus; also rostrate.
• bilabiate: two-lipped.
• callus: zone at base of pappus at its point of attachment to the achene.
• capitulescence: see inflorescence.
• capitulum [pl. capitula]: the organ where the florets are surrounded by primary phyllaries (involucral bracts) - the 'inflorescence' of the Compositae; also calathia.
• carpopodium: basal callus of achene, representing the abscission zone.
• discfloret: actinomorphic usually hermaphrodite, functionally male or sterile florets in the middle of the capitulum.
• disciform: a capitulum bearing outer filiform florets and inner tubular disc florets.
• discoid: a capitulum bearing identical florets all with tubular corollas.
• floret: the diminutive flower in the Compositae capitulum.
• flowering stem: the main stem of the inflorescence.
• glomerule: a small compact cluster usually representing a secondary aggregation of capitula, also a synflorescence.
• glomerulescence: the whole flowering structure made up of glomerules.
• heterogamous: a capitulum bearing two different types of florets, usually ray and disc florets.
• homogamous: a capitulum in which all florets are identical and usually hermaphrodite, but also all male florets, or all female in dioecious taxa.
• inflorescence: the whole flowering structure, including all capitula on the flowering stem.
• inflorescence branch: a branch, off of the peduncle or flowering stem, bearing one or more capitula.
• infructescence: a cluster of fruits derived from an inflorescence.
• involucre: the part of the capitulum made up of the phyllaries.
• ligulate: bearing a strap-shaped corollalimb with five teeth at its apex, or referring to a capitulum of ligulate florets.
• ligule: a corollalimb with five teeth at its apex.
• limb: the extended portion of a corolla, e.g. ray limb.
• palea (pl. paleae): sub-floral bracts found on the receptacle either as hairs or scales.
• pappus: considered to be the modified remnant of the calyx, usually capillary but sometimes scale-like or coroniform.
• pedicel: the ultimate branch of an inflorescence bearing a capitulum.
• peduncle: the common stalk of the inflorescence bearing several capitula (which may be borne on inflorescence branches).
• phyllary: an involucral bract.
• plumose: feather-like, usually referring to a pappus seta bearing lateral branches whose length are more than the diameter of the main seta.
• radiant: a capitulum with inner hermaphroditedisc florets and outer enlarged steriledisc florets.
• radiate: a capitulum with outer ray florets and inner disc florets.
• ray: the predominant limb of the outer florets in a heterogamous capitulum.
• ray floret: the outermost florets in a heterogamous capitulum bearing a ray limb.
• receptacle: the common area of attachment of the florets in the capitulum.
• scape: a leafless inflorescencestem bearing a single capitulum or synflorescence.
• seta (pl. setae): a bristle or stiff hair, usually a unit of a pappus.
• setuliferous: short stiff bristly pubescence, usually pertaining to the pubescence of an achene.
• squamellum (pl. squamellae): a broadened bristle or scale-like unit of the pappus.
• stipe: a stalk.
• style arm: the upper divisions of the style.
• subplumose: almost feather-like, usually referring to a pappus seta bearing lateral branches whose length is slightly less than the diameter of the seta.
• subradiate: a heterogamous capitulum with the outer florets bearing rays not exceeding the phyllaries.
• synflorescence: a conglomeration of capitula enclosed in secondary or tertiary involucres borne on a secondary receptacle; also syncalathium.
• vallecular canal: usually a resin canal opposite a longitudinal sulcus.
• xylopodium: woody subterranean rootstock, sometimes slightly fleshy.

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.

Number of genera

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

Literature

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.

Hind, D.J.N. (2011 onwards).  Preliminary checklist (with keys to genera) of the Compositae (Asteraceae) of Bolivia.  http://www.kew.org/science/tropamerica/boliviacompositae/index.html.