Facelis retusa (Lam.) Schulz–Bip., annual trampweed. Annual, taprooted, not rosetted, 1—several–stemmed at base, primary shoot erect, often with decumbent basal branches becoming suberect shoots, branching only in canopy, in range 3—< 20 cm tall; gynomonoecious; shoots with only overlapping cauline leaves, foliage bicolor with upper surface green and lower surface grayish white having white woolly hairs, minutely and with inconspicuously glandular–hairy beneath wool.
Stems cylindric, to 2 mm diameter (no decurrent leaf bases), with white, fine woolly hairs parallel along axis.
Leaves helically alternate, simple and sessile, without stipules; blade spreading to ascending, spatulate (the lowest cauline leaves) to linear but the widest at top, 6—19 × 1—3 mm, long–tapered at base, entire but most blades inrolled under (revolute), narrowly wedge–shaped and ± truncate with or without short point at tip, the point + top margin mostly deflexed (appearing retuse), 1–veined with midrib conspicuously sunken on upper surface and raised on lower surface, upper surface appearing glabrate with scattered fine hairs but having denser hairs along sunken midrib, lower surface with dense cover of woolly hairs but less hair along raised midrib.
Inflorescence head, 1—several in cluster at top of axillary peduncle, head ca. 3 mm across, of 10—25 pistillate and 3—5 central bisexual disclike flowers (disciform), flowers never exposed (enclosed within involucre), bracteate; peduncle cylindric, short—10 × 0.6—0.7 mm, flexible, white, white–woolly; bracts subtending head several, leaflike with revolute margins, to 6 mm long; involucre narrowly ovoid, in range at anthesis ca. 7 × 3 mm increasing 2 mm and slightly wider in fruit, phyllaries ca. 30 in ± 5 series, appressed, polymorphic, of the outermost series 5—6, obtuse–ovate and translucent, (1—)2—3 × 1.5 mm, in series becoming longer, elliptic, and mostly scarious–translucent to oblanceolate with green tissue above midpoint and scarious–translucent above, inner phyllaries ca. 11, strap–shaped, 7—9 mm long, mostly green, finely 3–veined at base, in range purplish at acute tip (purple clearly visible in fruit); receptacle flat, lacking bractlets (paleae) but with inconspicuous, a low, crownlike ridge around most ovaries, glabrous.
Pistillate flower radial, < 1 mm across; calyx (pappus) of about 25 soft, feathery (plumose) bristles fused in 1 series into a ring at base, at anthesis 5—5.5 mm long increasing 2× in fruit, initially erect and ca. 2 mm longer than corolla; corolla minutely 5–lobed (teeth), white, glabrous; tube + throat ca. 3 × 0.15 mm; teeth erect, acute, 0.15 mm long; stamens absent; pistil 1; ovary inferior, obovoid, ca. 0.8 mm long, greenish, covered with hairs 0.5—1.2 mm long, the shorter hairs with minute glandular heads, the longest ones next to pappus and appearing like an outer series of bristles, 1–chambered with 1 ovule; style included, threadlike, ca. 0.1 mm diameter, white, 2–forked, the stigmatic branches ca. 0.5 mm long, papillate.
Bisexual flower radial, < 1 mm across; calyx (pappus) of about 25 soft, feathery (plumose) bristles fused in 1 series into ring at base, at anthesis 5—5.5 mm long increasing 2× in fruit, initially erect and ca. 1 mm longer than corolla; corolla minutely 5–lobed (teeth), glabrous; tube + throat ca. 5 × 0.25 mm, white except purple at top; teeth erect, acute, 0.15 mm long, dark purple; stamens 5, attached to midpoint of corolla; filaments threadlike, ca. 2 mm long, white; anthers fused into cylinder surrounding style, basifixed, dithecal, included, 0.8 mm long, yellowish, longitudinally dehiscent; pollen yellowish; pistil 1; ovary inferior, obovoid, ca. 0.8 mm long, greenish, covered with hairs 0.5—1.2 mm long, the shorter hairs with minute glandular heads, the longest ones next to pappus and appearing like an outer series of bristles, 1–chambered with 1 ovule; style included, threadlike, ca. 0.1 mm diameter, white, 2–forked, the stigmatic branches within anthers, ca. 0.5 mm long, purplish, papillate; nectary disc surrounding base of style, ca. 0.3 mm long, greenish.
Fruits cypselae (achenes), monomorphic, obovoid somewhat compressed, in range ca. 1.2 mm long, densely covered with ascending, white, straight hairs 0.5—1.2 mm long, the longest at the top of cypsela and about as long as the fruit, the shorter hairs on faces of fruit body often with minute glandular heads; pappus of plumose bristles, 10—11 mm long, silky white, conspicuously exserted tuft from obovoid involucre 3—3.5 mm, when involucre dry (spreading phyllaries) pappus bristles spreading.
A. C. Gibson