6. Tribe Gnaphalieae Benth.
Plants annual or
perennial herbs (woody elsewhere), sometimes entirely or incompletely
dioecious, fibrous-rooted or taprooted, sometimes with rhizomes or stolons,
usually densely pubescent with white to grayish white woolly hairs, the sap not
milky. Stems unbranched or branched, not spiny or prickly. Leaves basal and
alternate, not spiny or prickly, sessile or with short, poorly differentiated
petioles. Leaf blades simple, the margins entire or with a few small teeth
(more divided elsewhere). Inflorescences terminal and sometimes also axillary
spikes, racemes, or flat-topped to headlike clusters, these sometimes grouped
into small panicles. Heads appearing discoid, with usually numerous florets.
Involucre cylindrical to ovoid or hemispherical, with few to several unequal series
of overlapping bracts, these appressed or spreading at maturity, at least
partially white to straw-colored or purplish-tinged, scalelike or papery, not
spiny or tuberculate, often all or partially obscured by dense pubescence.
Receptacle usually flat, less commonly convex or concave, naked or with chaffy
scales in Diaperia. Central florets (except in dioecious taxa) perfect
or staminate (the style branches not or only slightly spreading at maturity).
Marginal florets (except in staminate plants of dioecious taxa) pistillate
(lacking stamens). Corollas very slender, tubular, with very short lobes.
Pappus absent (in Diaperia) or more commonly of capillary bristles (awns
or scales elsewhere), these finely toothed or barbed (plumose elsewhere),
sometimes somewhat expanded and narrowly club-shaped at the tip, free or
sometimes fused at the base, usually shed before fruiting. Stamens with the
filaments not fused together, the anthers fused into a tube, each tip with a
short, sometimes indistinct appendage, each base prolonged into a pair of short
lobes. Style branches usually somewhat flattened, each with a stigmatic line
along each inner margin, the sterile tip rounded or more commonly truncate,
hairy. Fruits relatively small, variously shaped, not winged, not beaked,
glabrous, hairy, or with minute papillae. About 180 genera, about 2,000
species, worldwide.
Traditionally,
the genera treated here as tribe Gnaphalieae were included in an expanded
concept of Inuleae (Steyermark, 1963; Cronquist, 1980; Gleason and Cronquist,
1963, 1991; Barkley, 1986). Anderberg (1991, 1994), using morphological and
anatomical data, and Panero and Funk (2002), using molecular data, have shown
that this group has closer affinities to the Astereae and Anthemideae than to
the Inuleae and Plucheeae. In spite of this, the limits of the tribe
Gnaphalieae remain less than perfectly understood, and some generic limits
within the group also require further study. In the absence of data to the
contrary, the present treatment of generic limits follows that of the
forthcoming Flora of North America treatment more for expediency than out of
full confidence that the relatively finely split genera in that volume will
withstand the test of time.