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.
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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