Flora of North America species comparison

Genera ca. 187, species ca. 1240 (19 genera, 111 species in the flora).

Traditionally, taxa included here in Gnaphalieae have been treated in Inuleae within Gnaphaliinae (cf. A. A. Anderberg 1991; K. Bremer 1994). Gnaphalieae include everlastings and helichrysums, which have brightly colored, persistent phyllaries and are much used in dried floral arangements, and other ornamentals, e.g., species or cultivars from Anaphalis, Antennaria, and Leontopodium (edelweiss). Some species of Facelis, Gamochaeta, Gnaphalium, Helichrysum, and Pseudognaphalium are widespread as weeds.

Phyllaries in most Gnaphalieae are usually more or less herbaceous to more or less cartilaginous medially and/or proximally and membranous to scarious laterally and distally. The herbaceous to cartilagionous area of a phyllary is usually somewhat thicker than the rest and such areas are called stereomes. Stereomes may be more or less divided or not and may be more or less glandular or not. The membranous to scarious portion of a phyllary distal to the stereome is sometimes called a lamina (not to be confused with corolla laminae of other groups). The phyllaries, or laminae are often colored and may be more or less opaque or more or less hyaline.

Surfaces of cypselae of Gnaphalieae may be smooth, longitudinally ridged, or papillate (with minute bumps or projections from one or both ends of each epidermal cell; see A. A. Anderberg 1991). In addition, the cypselae may be glabrous or may bear myxogenic (producing mucilage when wetted) or non-myxogenic “twin-hairs.” The twin-hairs may be relatively long and form sericeous to strigillose induments. Very short, globose to clavate twin-hairs (lengths equaling or not much greater than diameters) are characteristic of some taxa and have sometimes been called “papillae” in descriptions of members of Gnaphalieae. Cypselae with such very short twin-hairs are described here as minutely hairy and the hairs are referred to as papilliform.

Stuartina hamata Philipson, a member of Gnaphalieae, was collected near a wool mill in South Carolina in 1957 (G. L. Nesom 2004c). It is native to Australia and may be characterized as annuals, prostrate, mostly 6–12 cm across, ± woolly, leaves cauline (crowded near heads), petioles basally dilated, blades suborbiculate, heads ca. 3 mm (borne in glomerules), phyllaries ovate to lanceolate, inner uncinate, florets 5 (outer 4 pistillate, inner bisexual), cypselae 0.8–1 mm, epappose.

Genera 97–105 below (genera following second lead 3 in key to genera, members of Filagininae in a narrow sense) have exceptionally small heads and florets (even for composites) and are closely similar in expressions of some characters. Together, as found in the flora, they may be characterized as:

Annuals, taprooted, usually arachnoid-sericeous to lanuginose throughout, sometimes glabrescent proximally on stems and/or on adaxial faces of leaves. Leaves usually sessile, sometimes obscurely petiolate (usually gradually larger and more crowded distally, sometimes again smaller among heads, where referred to as capitular leaves); blades 1-nerved, bases usually ± cuneate, sometimes rounded, margins entire. Heads disciform. Involucres absent, vestigial, or inconspicuous, often simulated by leaves or paleae. Phyllaries 0, vestigial, or 1–6. Receptacles paleate (at least peripherally), usually glabrous among paleae (bristly in Hesperevax). Florets pistillate, functionally staminate (usually referred to as staminate), or bisexual; corollas whitish, usually distally yellowish, reddish, brownish, or purplish.

Leaves of Filagininae that immediately subtend heads and/or glomerules are here called capitular leaves. Flowering branches may also immediately subtend heads or glomerules; if so, capitular leaves collectively subtend such branches and their heads/glomerules, and heads/glomerules appear to be sessile in forks of pseudo-dichotomies or -polytomies. Sometimes capitular leaves subtend only glomerules and not individual heads and individual heads may be difficult to distinguish within glomerules.

Paleae subtend all or at least some florets in members of Filagininae. They are referred to as bisexual, pistillate, or staminate paleae depending on sorts of florets subtended. Pistillate paleae persistent or shed with cypselae, usually incurved over inner (bisexual or functionally staminate) florets at flowering; margins usually thinner, ± scarious, forming wings (sometimes gradually and obscurely so); wings recurved to erect to incurved or inflexed; abaxial faces usually ± lanuginose to sericeous, sometimes glabrate or glabrous; apices rounded or obtuse to acuminate or aristate. Bisexual and/or staminate paleae usually persistent, sometimes falling in fruit, sometimes 0 (most Filago, Logfia, and Micropus, all Psilocarphus; then simulated by pistillate paleae), usually erect at flowering, incurved, erect, or spreading in fruit, sometimes enlarging as cypselae mature (then adaxially lanuginose to sericeous), shorter than or surpassing pistillate paleae; bodies ± ovate or lanceolate to spatulate (saccate in Micropsis); margins rarely forming wings; abaxial faces lanuginose to sericeous or nearly glabrous; apices usually entire, sometimes 2–3-fid, sometimes aristate to spinose (uncinate in Ancistrocarphus filagineus).

Corolla scars on cypselae of Filagininae may be offset adaxially to subapical or ± median positions and may be diagnostic for certain taxa (corolla attachments usually appear to be apical before ovaries mature).

All or outer pistillate florets of Filagininae lack pappi. Inner pistillate, bisexual, and staminate florets have pappi 0 or of 1–28+, whitish, fragile (easily broken or detached) or readily falling, ± barbellate to barbellulate or smooth (sometimes smooth only distally) bristles in 1 series. At bases of bristles, barbs are sometimes notably longer and finer, sometimes wavy or curled, and more patent than antrorse and may interweave, resulting in proximal coherence of adjacent bristles (e.g., in Logfia); cohering bristles may be shed in groups or complete rings and separate subsequently.

In descriptions of Filagininae, median refers to areas or positions about midway between a base and corresponding apex, and medial refers to areas or positions ± centered between opposing lateral edges.

As noted by A. Cronquist (1950) for Psilocarphus, the wings or apices of pistillate paleae of Filagininae are incurved during flowering, guide styles over bisexual or functionally staminate florets, and, likely, enforce nearly obligate within-head geitonogamy. Reproductive isolation created by this self-pollinating syndrome may allow interspecific or intergeneric hybrids, when fertile, to persist and become independently reproducing species among their parental taxa (J. D. Morefield 1992, 1992b).

Birds harvest shoots of Logfia, Micropus, Psilocarphus, and Stylocline species, presumably for nesting materials (neststraw is common name for Stylocline) and may be significant in shorter-distance dispersal of some taxa. The light, fluffy paleae enclosing epappose cypselae of the same genera aid in wind dispersal, as suggested by A. Cronquist (1950).

Different species and genera of Filagininae often grow together and are frequently mixedand/or misidentified on herbarium sheets. Young or stunted plants often will not fit keys and descriptions; whenever practicable in attempting identifications of members of Filagininae, use well-developed plants with at least some heads in fruit. Some diagnostic characters require careful evaluation of structures within heads, usually with magnification; for example, anther tips and corolla lobes may be similar in color and shape and may be difficult to distinguish.

Good illustrations of most North American Filagininae may be found in L. Abrams and R. S. Ferris (1923–1960, vol. 4), G. Beauverd (1913), or J. C. Hickman (1993).

Genera ca. 187, species ca. 1240 (19 genera, 111 species in the flora)

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 50 (12 in the flora).

Gamochaeta comprises about 50 species (A. L. Cabrera 1961; S. E. Freire and L. Iharlegui 1997) or about 80 species (Cabrera 1977+, part 10), all native to the Americas. Most are known only from South America; some apparently are native to Mexico and the flora area (G. L. Nesom 2004b). Some species are strongly weedy and have extended non-native ranges. Because of inconsistencies in the identification of those species, it has been difficult to evaluate the overall distributions of the widespread species.

The distinctiveness of Gamochaeta was emphasized by A. L. Cabrera (1961, and in later floristic treatments of South American species) and by other botanists who have treated it as a separate genus in the last decade. The genus is distinguished by its combination of relatively small heads in spiciform arrays, concave post-fruiting receptacles, truncate collecting appendages of style branches in bisexual florets, relatively small cypselae with minute, mucilage-producing papilliform hairs on the faces, and pappus bristles basally connate in smooth rings and released as single units. It seems likely that most species are primarily autogamous, in view of the tiny, non-showy heads that barely open through flowering. The consistency of vegetative and floral features in some of the species supports this hypothesis.

In the flora area, some species have commonly been treated as variants within Gamochaeta purpurea; distinctions are evident in the field, where it is common to find as many as five species growing in proximity without intergradation. Species of Gamochaeta are distinguished by differences primarily in root form, leaf shape, nature and distribution of indument, and phyllary morphology. Chromosome counts have been reported for some species; because of the unreliability of identifications, vouchers for those counts should be restudied.

(Discussion copyrighted by Flora of North America; reprinted with permission.)