Portulaca

Herbs, annual (perennial in P. suffrutescens). Roots tuberous, fleshy, fibrous, or small taproots. Stems erect to prostrate, branched, fleshy or suffrutescent; trichomes in inflorescence or stem nodes absent or present, glabrous otherwise. Leaves alternate or subopposite, congested and involucrelike immediately proximal to inflorescence; blade terete, subterete, or flattened. Inflorescences terminal in clusters, or axillary on short branches. Flowers sessile or subsessile, usually open only in sunshine; sepals broadly clasping at base, herbaceous to scarious, falling from top of capsule; petals ephemeral, 5–7, usually distinct, margins usually entire; stamens (4–)6–40(–100); ovary half inferior to inferior, plurilocular proximally to 1-locular distally, placentation free-central; style 1, short, stigmas 3–8(–18). Capsules membranaceous, chartaceous, dehiscence circumscissile. Seeds many, brown to black or gray, reniform to cochleate; seed coat smooth or variously sculptured, granular to stellate-tuberculate or spiny. x = 4, 5, 8, 9.

Distribution

Nearly worldwide, primarily tropical and subtropical, also temperate.

Discussion

Species 100–125 (10 in the flora).

Selected References

Legrand, C. D. 1962. Las especies Americanas de Portulaca. Anales Mus. Hist. Nat. Montevideo, ser. 2, 7: 1–147.

Matthews, J. F. and P. A. Levins. 1985. The genus Portulaca in the southeastern United States. Castanea 50: 96–104.

Walters, S. M. 1964. Portulaca. In: T. G. Tutin et al., eds. 1964–1980. Flora Europaea. 5 vols. Cambridge. Vol. 1, p. 114.

Wilson, P. 1932b. Portulaca. In: N. L. Britton et al., eds. 1905+. North American Flora.... 47+ vols. New York. Vol. 21, pp 328–336.

Lower Taxa

Portulaca amilis, Portulaca biloba, Portulaca grandiflora, Portulaca halimoides, Portulaca oleracea, Portulaca pilosa, Portulaca rubricaulis, Portulaca smallii, Portulaca suffrutescens, Portulaca umbraticola

Keys

Key Based on Flowering Material

1	Petals pink to purple	> 2
1	Petals yellow, orange, copper, bronze, or white	> 6
2	Flowers 25 mm or more diam.; petals 15 mm or longer	Portulaca grandiflora
2	Flowers to 25 mm diam.; petals 12 mm or shorter	> 3
3	Leaf blades flattened, 2-12 mm wide, obovate to spatulate or oblanceolate	Portulaca amilis
3	Leaf blades terete to hemispheric, 0.5-3 mm wide, linear to lanceolate	> 4
4	Petals deeply 2-lobed; stamens 40 or more; stem nodes with inconspicuous trichomes; restricted to sandstone outcrops in s Georgia	Portulaca biloba
4	Petals not 2-lobed; stamens usually fewer than 30; stem nodes with conspicuous trichomes; widespread in United States	> 5
5	Petals medium pink to almost white; seeds 0.6 mm or more diam., elongate; restricted to granitic outcrops in Georgia, North Carolina, South Carolina, Virginia	Portulaca smallii
5	Petals dark pink to purple; seeds 0.6 mm or less diam., orbiculate; wide- spread throughout se, lower Midwest, and sw United States	Portulaca pilosa
6	Flowers 25 mm or more diam	> 7
6	Flowers 20 mm or less diam	> 8
7	Plants perennial; roots tuberous; stems stiffly erect; sw United States	Portulaca suffrutescens
7	Plants annual; roots fibrous; stems prostrate to suberect; widespread	Portulaca grandiflora
8	Leaf blades terete to hemispheric, linear to lanceolate, usually 3 mm or less wide	> 9
8	Leaf blades flattened, obovate or spatulate (sometimes lanceolate in P. umbraticola), 2-15 mm or more wide	> 10
9	Stem nodes and inflorescences with conspicuous trichomes; flowers less than 8 mm diam.; Midwest and sw United States	Portulaca halimoides
9	Stem nodes and inflorescences with inconspicuous trichomes; flowers more than 9 mm diam.; tropical Florida	Portulaca rubricaulis
10	Capsules encircled by expanded, membranaceous wing	Portulaca umbraticola
10	Capsules not winged	Portulaca oleracea

Key Based on Fruiting Material

1	Capsules each encircled by expanded, membranaceous wing	Portulaca umbraticola
1	Capsules not winged	> 2
2	Leaf blades flattened	> 3
2	Leaf blades terete to hemispheric	> 4
3	Trichomes at stem nodes absent or inconspicuous; seeds 0.6-1.1 mm or more diam.	Portulaca oleracea
3	Trichomes at stem nodes conspicuous; seeds 0.4- 0.6 mm or less diam	Portulaca amilis
4	Stem nodes with inconspicuous trichomes	> 5
4	Stem nodes with conspicuous trichomes	> 6
5	Seeds 0.7 mm or more diam., surface cells distinctly stellate, tuberculate	Portulaca biloba
5	Seeds less than 0.7 mm diam., surface cells obscurely stellate, without tubercles	Portulaca rubricaulis
6	Seeds 0.6-1 mm diam	> 7
6	Seeds 0.3-0.65 mm diam	> 8
7	Longest leaves usually longer than 20 mm; capsules usually more than 4 mm diam	Portulaca grandiflora
7	Longest leaves usually shorter than 15 mm; capsules 3.5 mm or less diam.	Portulaca smallii
8	Capsules 2 mm or less diam.; lateral seed coat with densely arranged, flattened, stellate cells, tubercles absent; seeds averaging 0.5 mm or less diam.	Portulaca halimoides
8	Capsules 1.5-5 mm diam.; seed coat with loosely arranged, stellate cells; tubercles usually present; seeds averaging more than 0.5 mm diam	> 9
9	Plants annual; roots fibrous to slightly fleshy; stems prostrate or suberect to erect	Portulaca pilosa
9	Plants perennial; roots tuberous; stems stiffly erect	Portulaca suffrutescens