Gomphrena

Linnaeus

Sp. Pl. 1: 224. 1753

Gen. Pl. ed. 5, 105. 1754

Etymology: Latin gromphaena, a type of amaranth
Treatment appears in FNA Volume 4. Treatment on page 451. Mentioned on page 406.
Herbs, annual or perennial. Stems ascending, decumbent, prostrate, or erect. Leaves opposite, sessile or petiolate; blade ovate to obovate, not fleshy, margins entire, long-pilose abaxially and sometimes adaxially. Inflorescences terminal and/or axillary, sessile, subglobose heads, often subtended by involucres of sessile leaves; bracts and bracteoles thin. Flowers bisexual; tepals 5, connate proximally; stamens 5; filaments connate basally into tube; pseudostaminodes absent; ovule 1; style 1, 1.5–4 mm; stigmas 2(–3), subulate or filiform. Utricles included in tepals, stramineous, ovoid or oblong, somewhat compressed, membranous, usually indehiscent. Seeds 1, lenticular, subglobose, to ovoid, smooth.

Distribution

Tropical, subtropical, and warm-temperate regions.

Discussion

Species ca. 100 (9 in the flora).

Key

1 Bractlets not cristate > 2
1 Bractlets cristate along keel > 5
2 Plants cespitose 3-15 cm; stems with 1-2 pairs of leaves > 3
2 Plants not cespitose, 4-60 cm; each stem bearing numerous leaves > 4
3 Leaf blades green, very sparsely villose, glabrate; blades of cauline leaves longer than broad Gomphrena viridis
3 Leaf blades gray, densely villose; blades of cauline leaves as broad as long Gomphrena caespitosa
4 Flower tubes glabrous; inflorescence heads not subtended by 2 leaves Gomphrena martiana
4 Flower tubes lanose proximally; inflorescence heads subtended by 2 leaves Gomphrena sonorae
5 Roots fleshy, fusiform; plants perennial > 6
5 Roots fibrous; plants annual or sometimes perennial (G. serrata) > 7
6 Leaf blades 1.5-4 cm, apex rounded; perianth 4.5-4.7 mm Gomphrena nealleyi
6 Leaf blades 3-10 cm, apex acute to acuminate; perianth ca. 5.3 mm Gomphrena haageana
7 Inflorescence heads 20-28 mm diam Gomphrena globosa
7 Inflorescence heads 8-16 mm diam > 8
8 Bractlets with denticulate crests; inflorescence heads 9-13 mm diam., usually tinged with red or pink; stems usually decumbent Gomphrena serrata
8 Bractlets with laciniate crests; inflorescence heads 12-16 mm diam, yellowish white, rarely reddish; stems usually erect Gomphrena nitida