FNA: Portulacaceae vs. Portulaca

Distribution

Primarily Southern Hemisphere; poorly represented in Eurasia

Nearly worldwide; primarily tropical and subtropical; also temperate

Discussion

Genera 20–30, species ca. 500 (9 genera, 91 species in the flora).

The eastern New World species of Portulacaceae seem to have a closer relationship with the African species, and the western New World species a closer one with the Australian species, than the two New World groups have with each other to each other.

The outer perianth segments, referred to herein as sepals, are held by some (e.g., T. Eckardt 1976) to be modified bracteoles, the petals then representing the true sepals. However, the traditional interpretation, adopted here and in most North American floras, still finds current support (R. C. Carolin 1987). A comparable situation prevails with respect to the cauline leaves in Claytonia and other genera, which are widely interpreted to be foliaceous bracts (R. C. Carolin 1987); here again, as is appropriate in a descriptive context, the traditional terminology is employed. In Talinopsis and Portulaca, the stipular nature of the nodal or axillary hairs also has been a matter of discussion. The question was revisited by R. Geesink (1969), who denied their stipular origin.

The relationships of the family are not a matter of dispute (A. Cronquist 1981; R. C. Carolin 1987); the same cannot be said for the relationships and delimitations of the genera, which have always been labile. They are, at present, the subject of active research, which has led to the current acceptance of Phemeranthus and Cistanthe. Changes in the generic classification are discussed in the treatments of the genera concerned.

Because of the uncertain relationships, the genera and species are listed alphabetically.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 100–125 (10 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key

1. Ovary half-inferior to inferior	Portulaca
1. Ovary superior	→ 2
2. Subshrubs; stem nodes pubescent	Talinopsis
2. Herbs; stem nodes glabrous	→ 3
3. Capsule dehiscence circumscissile, valves longitudinally dehiscent from base	→ 4
3. Capsule dehiscence not circumscissile, valves longitudinally dehiscent from apex	→ 5
4. Petals 25-40 mm; seeds strophiolate; nc Washington to extreme sc British Columbia	Cistanthe
4. Petals 4-26 mm (15-35 mm in Lewisia rediviva); seeds estrophiolate; more widespread	Lewisia
5. Stigmas 2; capsule valves 2	Cistanthe
5. Stigmas 1 or 3; capsule valves 2-3	→ 6
6. Sepals mostly deciduous; inflorescences not appearing secund; leaves articulate at base, attachment points round, not clasping; capsule valves wholly or partly deciduous	→ 7
6. Sepals persistent; inflorescences somewhat to markedly secund (at least distally); leaves not articulate at base, attachment points linear, somewhat to markedly clasping; capsule valves not deciduous	→ 8
7. Leaf blades broadly planate, 1-7 cm wide; capsules tardily dehiscent, valves or portions of them sometimes persistent; exocarp and endocarp distinctly differentiated, sometimes separating; seeds minutely tuberculate or striolate, strophiolate, not covered by membrane	Talinum
7. Leaf blades terete or semiterete, 1-3 mm wide, (narrowly planate, 1[-2] cm wide in Phemeranthus aurantiacus); capsules promptly dehiscent, valves deciduous; exocarp and endocarp not evidently differentiated and not separating; seeds smooth, rugulose, or distinctly ridged, estrophiolate, covered by thin, fleshy to chartaceous membrane	Phemeranthus
8. Ovules and seeds (1-)7-40	→ 9
8. Ovules 3 or 6; seeds 1-6	→ 10
9. Leaves and sepals sometimes with elongate, unicellular hairs; sepals distinctly angular or keeled; capsule valves reflexed after dehiscence, margins markedly involute	Calandrinia
9. Leaves and sepals without elongate, unicellular hairs; sepals not distinctly angled or keeled; capsule valves not reflexed after dehiscence, margins not markedly involute	Cistanthe
10. Cauline leaves 2 (rarely 3 in whorl), distinct or partially or completely connate; ovules 3 or 6	Claytonia
10. Cauline leaves more than 2, distinct; ovules 3	Montia

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	P. 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	P. 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	P. 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	P. 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	P. 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	P. suffrutescens
7. Plants annual; roots fibrous; stems prostrate to suberect; widespread	P. 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	P. halimoides
9. Stem nodes and inflorescences with inconspicuous trichomes; flowers more than 9 mm diam.; tropical Florida	P. rubricaulis
10. Capsules encircled by expanded, membranaceous wing	P. umbraticola
10. Capsules not winged	P. oleracea

Key Based on Fruiting Material

1. Capsules each encircled by expanded, membranaceous wing	P. 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.	P. oleracea
3. Trichomes at stem nodes conspicuous; seeds 0.4- 0.6 mm or less diam	P. 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	P. biloba
5. Seeds less than 0.7 mm diam., surface cells obscurely stellate, without tubercles	P. 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	P. grandiflora
7. Longest leaves usually shorter than 15 mm; capsules 3.5 mm or less diam.	P. 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.	P. 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	P. pilosa
9. Plants perennial; roots tuberous; stems stiffly erect	P. suffrutescens