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spreading sandwort

trans-Pecos sandwort

Habit Plants ± strongly perennial, possibly blooming first year, not matted. Plants annual.
Taproots

filiform to moderately thickened;

rhizomes often present, slender, 2–15+ cm.

filiform.

Stems

1–80+, erect or ascending to procumbent or prostrate to trailing, green, 5–60 cm;

internodes terete to angular, 1/3–8+ times as long as leaves, dull, retrorsely pubescent throughout or in lines, hairs minute.

1–18+, erect to ascending, green or reddish, 15–30(–45) cm;

internodes ± terete, 1–10 times as long as leaves, dull, retrorsely pubescent in 2 lines.

Leaves

usually connate basally, with scarious sheath 0.1–0.5 mm, occasionally petiolate (proximal leaves) or sessile;

petiole 2–5 mm;

blade 1-veined, vein prominent abaxially, linear-lanceolate to narrowly elliptic or oblanceolate, 3–35 × 2–14 mm, herbaceous, margins thickened, scarious, shiny, ciliate proximally or throughout, apex obtuse or acute to apiculate, often minutely pustulate, ciliate on margins and adaxial midrib;

axillary leaf clusters absent.

usually connate basally, with narrow, scarious sheath 0.2–0.5 mm, petiolate (proximal leaves) or sessile;

petiole 2–4 mm;

blade 1-veined, vein prominent abaxially, usually narrowly lanceolate, elliptic, or oblanceolate, 10–17 × 2–4 mm, herbaceous, margins ± flat, herbaceous, dull, ciliate in proximal 1/2, apex acute to acuminate, not pustulate, glabrous;

axillary leaf clusters absent.

Inflorescences

axillary, solitary flowers or in proliferating, mostly terminal, leafy, 1–80+-flowered cymes.

terminal, open, minutely bracteate, 3–45+-flowered cymes.

Pedicels

erect to ascending (often arcuately so), or straight to widely divergent, often hooked distally in fruit, 2–40 mm, retrorsely pubescent.

erect or ascending in fruit, 3–20 mm, retrorsely pubescent in 2 lines.

Flowers

sepals green, 1–3-veined, 2 lateral veins 1/4–3/4 times as long as midvein, often appearing prominently keeled proximally, lanceolate to ovate (herbaceous portion oblong or lanceolate to ovate), 2–5 mm, to 5.5 mm in fruit, apex acute to acuminate, not pustulate, glabrous;

petals narrowly spatulate to obovate, 1.5–6 mm, 1/2–12/5 times as long as sepals or absent, apex obtuse to rounded, petals sometimes absent.

sepals green or often purple, 1-veined, strongly keeled proximally, ovate-lanceolate to narrowly lanceolate (herbaceous portion pale, narrowly lanceolate to linear), 3–4 mm, not enlarging in fruit, apex acuminate, not pustulate, glabrous;

petals oblong to broadly elliptic, 2.8–4 mm, 1–11/3 times as long as sepals, apex rounded.

Capsules

± loosely to tightly enclosed by calyx, ovoid, 3–6 mm, 4/5–11/2 times as long as sepals.

loosely enclosed by calyx, ovoid, 3–3.5 mm, 4/5–1 times as long as sepals.

Seeds

8–35, black, suborbicular, slightly compressed, 0.7–0.8 mm, shiny, smooth.

7–15, dark brown to black, suborbicular, slightly compressed, 0.6–0.7 mm, shiny, obscurely tuberculate (20x).

2n

= 40, 44.

Arenaria lanuginosa

Arenaria ludens

Phenology Flowering late summer–early autumn.
Habitat Igneous soil on cliffs and ledges
Elevation 1000-2000 m (3300-6600 ft)
Distribution
from FNA
AL; AZ; CA; CO; FL; GA; LA; MS; NC; NM; SC; TN; TX; UT; VA; Central America; South America
[WildflowerSearch map]
[BONAP county map]
from FNA
TX; n Mexico (Coahuila)
[BONAP county map]
Discussion

Varieties 4+ (2 in the flora).

Arenaria lanuginosa is morphologically diverse, both in our area and southward into northern South America, and is in serious need of comprehensive study. Other species in subg. Leiosperma (e.g., A. gypsostrata B. L. Turner) that occur in Mexico resemble A. lanuginosa; the nature of those relationships also requires study. We have taken the “conservative approach” of treating the two taxa that occur in the flora area as varieties.

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

Arenaria ludens may be more closely related to A. lanuginosa than to A. benthamii, the taxon with which it is often confused, if seed morphology is any indication.

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

Key
1. Stems often 1-10, prostrate to trailing; inflorescences of solitary, axillary flowers; petals absent or 1/ 3/ 4 times as long as sepals
var. lanuginosa
1. Stems 1-80+, erect or ascending to procumbent; inflorescences of proliferating, leafy, 1-80+-flowered cymes; petals 3/ 2/ 5 times as long as sepals
var. saxosa
Source FNA vol. 5, p. 53. FNA vol. 5, p. 54.
Parent taxa Caryophyllaceae > subfam. Alsinoideae > Arenaria Caryophyllaceae > subfam. Alsinoideae > Arenaria
Sibling taxa
A. benthamii, A. humifusa, A. livermorensis, A. longipedunculata, A. ludens, A. paludicola, A. pseudofrigida, A. serpyllifolia
A. benthamii, A. humifusa, A. lanuginosa, A. livermorensis, A. longipedunculata, A. paludicola, A. pseudofrigida, A. serpyllifolia
Subordinate taxa
A. lanuginosa var. lanuginosa, A. lanuginosa var. saxosa
Synonyms Spergulastrum lanuginosum
Name authority (Michaux) Rohrbach: in C. F. P. von Martius et al., Fl. Bras. 14(2): 274. (1872) Shinners: Sida 1: 51. (1962)
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