Aphanes

Herbs, annual, prostrate to ascending, 0.1–3 dm, soft-hairy; taprooted. Stems 1–10+, erect, ascending, or spreading. Leaves not persistent, cauline, alternate, simple (deeply lobed); stipules persistent, free or distally adnate to petiole, asymmetric, ± orbicular to ovate, margins lobed; petiole present, short; blade cuneate, 0.2–1 cm, herbaceous, deeply divided into 2–3(–5) segments, each segment (1–)2–3(–6)-lobed, margins flat, entire, venation pinnate. Inflorescences lateral, 4–12-flowered, condensed cymes, often hidden by stipules; bracts absent; bracteoles absent. Pedicels present. Flowers 0.7–1.1 mm diam.; epicalyx bractlets (0–)4; hypanthium subglobose to ellipsoid or ovoid, 0.7–2 mm; sepals 4, connivent or erect to spreading, ovate to narrowly triangular; petals 0; stamens 1(or 2); torus absent or reduced; carpel 1, hairy, styles basal, stigmas capitate; ovule 1. Fruits achenes, 1, narrowly ovoid, 0.8–2.5 mm; hypanthium persistent; sepals persistent, erect; styles deciduous. x = 8.

Distribution

North America, nw Mexico, Eurasia, n Africa, introduced in s South America, Pacific Islands, Australia.

Discussion

Species ca. 20 (3 in the flora).

On the basis of molecular studies, R. Gehrke et al. (2008) have suggested that Aphanes and the Central America and South American Lachemilla (Focke) Rydberg should be included in a more broadly circumscribed Alchemilla. Both Aphanes and Lachemilla were shown to be monophyletic groups as is Alchemilla, apart from the African species currently placed in that genus; these form a clade separate from Alchemilla as represented in North America and Eurasia. The African species deserve more thorough investigation before such a morphologically distinct genus as Aphanes is abandoned.

The highly reduced nature of plants of Aphanes, coupled with their high dispersibility, complicates circumscription of species in the genus. The most recent treatments recognize a number of endemic species in South America, Europe, and North Africa, particularly in regions with Mediterranean climates. The extent to which these, and those recognizable in western North America, represent native radiations versus multiple introductions remains to be determined.

Measurements of flowers apply collectively to the length of the hypanthium and calyx measured in fruit.

Selected References

None.

Lower Taxa

Aphanes arvensis, Aphanes australis, Aphanes occidentalis

Key

1	Flowers 1.5–2.5 mm in fruit, sepals ± spreading to erect; leaf blades 4–10 mm; petioles free from stipules in proximal and distal leaves; stems 2–20(–30) cm; at least some hairs more than 1 mm; most stipule lobes on distal nodes ± triangular, 1–2(–4) times as long as wide.	Aphanes arvensis
1	Flowers 1–1.5 mm in fruit, sepals connivent to spreading; leaf blades 2–5 mm; petioles adnate to stipules in distal leaves; stems 1–10(–22) cm; hairs less than 1 mm; most stipule lobes on distal nodes oblong or ovate, usually 2/3–1 times as long as wide	> 2
2	Inflorescences dense, flowers tending to remain hidden; pedicels usually less than 1 mm; sepals 0.2 mm, connivent; epicalyx bractlets minute (less than 0.1 mm) or absent; stipules overlapping, lobes oblong, almost equal to undivided portion; leaf blades 5 mm, divided into 3 segments.	Aphanes australis
2	Inflorescences open, flowers tending to become exposed; pedicels to 2 mm; sepals 0.2–0.6 mm, connivent to spreading; epicalyx bractlets 0–0.5 mm; stipules overlapping only distally, lobes ovate, 2/3–1 times undivided portion; leaf blades 2–5 mm, 4–6-lobed.	Aphanes occidentalis