Lachnocaulon

Kunth

Enum. Pl. 3: 497. 1841

Common names: Hat-pins bog bachelor's buttons
Etymology: Greek lachnos, wool, and chaulos, stem, in reference to the long, soft, upwardly pointed hairs on scapes of the type
Treatment appears in FNA Volume 22.
Herbs, perennial, cespitose, rosulate. Roots branched, dark, not septate, slender, fibrous. Stems sparingly branched, short or elongate. Leaves crowded, in spirals; blade mostly linear, lacunar tissue not evident, base pale, dilated. Inflorescences: scape sheaths tubular, orifice oblique, acute, or 2-cleft; scapes usually several per stem, filiform, glabrous or hairy, hairs neither swollen nor glandular apically; heads white, gray, gray-brown, or brown, ovoid to globose or short-cylindric; receptacle densely pale-pilose; involucral bracts pale to dark, gradate, broad, chaffy, basal ones often reflexed, obscured by inflorescence; receptacular bracts as long as involucral bracts. Flowers: staminate and pistillate on same plants, 3-merous (2-merous in Lachnocaulon digynum); sepals 3, connivent forming club-shaped flower, nearly distinct, spatulate, scarious, apex with club-shaped hairs, surface glabrous or sparsely hairy; petals absent or reduced to small scales or hairs. Staminate flowers: androphore cylindric; stamens (2–)3; apex of staminal column with 2–3 lance-ovoid or peglike, often appendaged glands; filaments adnate to rim of androphore, alternating with glands; anthers 1-locular, 2-sporangiate, dorsifixed, versatile, exserted at anthesis, yellowish or pale. Pistillate flowers: gynophore short; pistil 3-carpellate (2-carpellate in L. digynum); style 1, appendaged at apex, style branches 2–3, 2-cleft, alternating with appendages similar to those of staminate flower.

Distribution

se United States and Cuba.

Discussion

Species ca. 10 (5 in the flora).

Selected References

None.

Key

1 Apical hairs of receptacular bracts and perianth white, mealy, opaque; heads pale gray to white; scapes hairy (except for glabrous-scaped, s Florida extreme of Lachnocaulon anceps). > 2
1 Apical hairs of bracts and perianth translucent, not white, the brown color of bract and perianth showing through; heads brown or gray-brown; scapes glabrous or with ascending hairs. > 3
2 Leaves narrowly linear, abruptly attenuate; mature heads seldom wider than 4 mm, dull gray-brown or pale gray; scapes glabrous or nearly so distally; seeds dark red-brown, very lustrous, longitudinal ribs faint, transverse ribs forming finely cross-striolate pattern Lachnocaulon beyrichianum
2 Leaves linear, gradually attentuate; mature heads seldom as narrow as 4 mm, whitish to pale gray; scapes pilose from base to apex; seeds pale to dark brown, not lustrous, longitudinal ribs conspicuous, transverse ribs less conspicuous than longitudinal ribs, but coarser than in Lachnocaulon beyrichianum Lachnocaulon anceps
3 Scapes with ascending hairs; heads dull gray-brown; hairs of receptacle copious, partly obscuring flowers (old heads may lose some hairs); gynoecium 3-carpellate Lachnocaulon minus
3 Scapes glabrous; heads either chocolate brown or dull brown, if dull brown, with sepals of pistillate flowers yellow-white, hardly obscured by receptacular hairs; gynoecium 2–3-carpellate. > 4
4 Heads dark brown or reddish brown, usually short cylindric by seeding time; gynoecium 3-carpellate; leaves 2–4 cm; scape sheaths shorter than or as long as leaves Lachnocaulon engleri
4 Heads gray or gray-brown, usually globose by seeding time; gynoecium 2-carpellate; leaves 0.5–2 cm, scape sheaths longer than or at least rising above leaves Lachnocaulon digynum