Lewisia oppositifolia
Portulacaceae
opposite-leaf lewisia
purslane family
gradually ramified distally.
erect, basal nodes underground, 10–20(–25) cm.
basal leaves withering at or soon after anthesis, abruptly narrowed into broad petiole, blade linear-spatulate to linear-oblanceolate, flattened, 4–11 cm, margins entire, apex obtuse to subacute;
cauline leaves opposite, in 1–3 pairs near stem base, smaller than and similar to basal leaves.
opposite, subopposite, or alternate and sometimes secund, sometimes rosulate or subrosulate, exstipulate (except Portulaca and Talinopsis, with nodal or axillary hairs regarded as stipular);
blade margins mostly entire, occasionally dentate to crisped.
racemose to subumbellate cymes, (1–)2–5(–6)-flowered;
bracts alternate proximally, 1–many at each flowering node distally, lanceolate, 4–8 mm, margins entire or toothed at apex, apex acute to acuminate.
axillary or terminal, cymose, racemose, paniculate, or umbellate, sometimes glomerate, spikelike, or with flowers solitary, open to congested.
pedicellate, not disarticulate in fruit;
sepals 2, suborbiculate, 4–8(–10) mm, herbaceous at anthesis, margins coarsely toothed but not glandular, apex obtuse to rounded;
petals 8–11, pink fading to white, oblanceolate to obovate, 9–15 mm;
stamens 8–18;
stigmas 3–5;
pedicel 20–75 mm.
mostly radially symmetric, sometimes slightly irregular (in Montia);
sepals 2–9;
petals (1–)2–19 or sometimes absent, distinct or connate basally;
stamens 1–many, opposite and sometimes basally adnate to petals;
gynoecium 2–9-carpelled;
ovary 1, superior (half-inferior to inferior in Portulaca), 1-locular throughout or initially plurilocular and becoming 1-locular distally (in Portulaca), placentation basal or free-central, ovules 1-many;
style present, sometimes branched, or absent;
stigmas 1–9.
capsular.
5–6 mm.
5–15, 1–1.8 mm, shiny, smooth.
smooth or sculptured, with or without strophioles or elaiosomes.
= 4–9, 11, 13, 15, 23.
Lewisia oppositifolia
Portulacaceae
Lewisia oppositifolia is known only from Del Norte County, California, and Josephine County, Oregon.
The floral symmetry of Lewisia oppositifolia may be somewhat elliptical, the outer two petals alternating with the sepals and the remaining petals imbricate and opposite the sepals, giving the flowers a pinched appearance, a feature also reported for L. nevadensis. The more diminutive, higher-elevation plants of L. oppositifolia possibly represent a distinct taxon that has been informally recognized as “Lewisia richeyi” (B. Mathew 1989b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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 |
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