FNA: Portulacaceae vs. Lewisia

Distribution

Primarily Southern Hemisphere; poorly represented in Eurasia

w North America (including Mexico)

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 16 (16 in the flora).

The number and circumscription of species in Lewisia are not widely agreed upon because of morphological variability and intergradation. Natural hybridization is inferred for some plants. In cultivation, the species reputedly freely intercross; most hybrid offspring are sterile. Most species are cultivated by alpine/succulent plant enthusiasts. In the wild, the plants usually occur in small, isolated populations in rocky or gravelly places, especially in canyons or alpine flats.

The key to species here has been modified from B. Mathew (1989b). Hybrids, cultivars, and plants in cultivation may not key satisfactorily.

(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

1. Roots globose, cormlike; basal leaves usually senescent before anthesis; cauline leaves in single pair or whorl of 3(-5)	L. triphylla
1. Roots elongate, gradually ramified distally, or fusiform to napiform; basal leaves evergreen or senescent at or immediately following anthesis; cauline leaves in more than 1 opposite pair or alternate, or absent	→ 2
2. Basal leaves evergreen	→ 3
2. Basal leaves senescing at or soon after anthesis	→ 6
3. Basal leaf blades linear to narrowly oblanceolate, margins entire	→ 4
3. Basal leaf blades oblanceolate, spatulate, obovate, orbiculate, or very rarely nearly linear, margins entire or toothed	→ 5
4. Leaves ± terete	L. leeana
4. Leaves flattened or adaxial surface grooved	L. columbiana
5. Petals 5-9 mm, white to pale pink with darker veins; cymes loosely paniculate	L. cantelovii
5. Petals (8-)10-20 mm, usually pink-purple with pale and darker stripes, less often white, cream with pink-orange stripes, ± orange, or yellow; cymes densely paniculate to subumbellate	L. cotyledon
6. Flowers sessile; bract and sepal pairs decussate and appearing to form 4-merous calyx	→ 7
6. Flowers pedicellate; bracts and sepals not resembling 4-merous calyx	→ 8
7. Sepal margins toothed, sometimes glandular; petals 10-15 mm	L. kelloggii
7. Sepal margins entire, not glandular; petals 12-26 mm	L. brachycalyx
8. Flowers disarticulate in fruit; sepals 2-9, scarious at anthesis, margins entire to somewhat erose, not toothed	→ 9
8. Flowers not disarticulate in fruit; sepals 2, herbaceous at anthesis, margins entire, toothed, or glandular-toothed	→ 11
9. Sepals (4-)6-9; petals 10-19; proximalmost bracts in whorl of 4-7(-8)	L. rediviva
9. Sepals 2-4; petals 5-9; proximal bracts in 1 pair or whorl of 3-4	→ 10
10. Sepals 2; petals 5-8; bracts ovate to lanceolate; flowers borne singly; s Sierra Nevada, California	L. disepala
10. Sepals 3-4; petals 7-9; bracts oblong to oblong-ovate; inflorescences 2-3-flowered or flowers borne singly; Nye County, Nevada	L. maguirei
11. Cauline leaves opposite, in 1-3 pairs, not markedly smaller than basal leaves	L. oppositifolia
11. Cauline leaves absent or alternate, markedly smaller than basal leaves	→ 12
12. Basal leaf blades oblanceolate, spatulate, or obovate; inflorescences paniculate or subumbellate cymes, 3-100-flowered	→ 13
12. Basal leaf blades linear to linear-oblanceolate; inflorescences 2-7-flowered racemose cymes or flowers borne singly	→ 14
13. Inflorescences 3-7-branched paniculate cymes, 20-100-flowered; petals 6-7, pale pink with yellow-green bases; stamens 4-5; Mari- posa County, California	L. congdonii
13. Inflorescences 1-3-branched subumbellate cymes, 3-11-flowered; petals 7-10, magenta or carmine with whitish bases; stamens 10-13; n Coast Ranges, California	L. stebbinsii
14. Flowers 2.5-4 cm diam.; Eldorado County, Nevada, and Placer County, California	L. longipetala
14. Flowers 0.5-2 cm diam.; more widely distributed	→ 15
15. Sepal margins mostly entire, sometimes obscurely or irregularly toothed, not glan- dular, apex acute to subacute; taproot napiform to shortly fusiform	L. nevadensis
15. Sepal margins regularly toothed, usually glandular-toothed (rarely ± entire), apex truncate or sometimes rounded, obtuse, subacute, or apiculate; taproot gradually ramified distally or shortly fusiform, rarely subnapiform	L. pygmaea