Arenaria lanuginosa
Arenaria livermorensis
spreading sandwort
Livermore sandwort
filiform to moderately thickened;
rhizomes often present, slender, 2–15+ cm.
filiform.
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.
15–25, decumbent, trailing, green, 1–4 cm;
internodes angular to grooved, 1–11/2 times as long as leaves, minute, shiny, pubescence of widely spreading to slightly retrorse hairs in 2 lines.
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.
connate basally, with herbaceous sheath 0.1–0.2 mm, sessile;
blade 1-veined, vein prominent abaxially, linear, 4–6 × 1 mm, herbaceous, rigid, margins thickened, herbaceous, shiny, lined with peglike cilia, apex acute, pungent-tipped, not pustulate, glabrous;
axillary leaf clusters present.
axillary, solitary flowers or in proliferating, mostly terminal, leafy, 1–80+-flowered cymes.
solitary flowers in distal leaf axils.
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, 6–10 mm, minutely pubescent.
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, 1-veined, slightly keeled proximally, broadly lanceolate (herbaceous portion narrowly lanceolate), 3–4 mm, not enlarging in fruit, apex acute to acuminate, not pustulate, glabrous;
petals absent;
stamens ca. 8.
± loosely to tightly enclosed by calyx, ovoid, 3–6 mm, 4/5–11/2 times as long as sepals.
very loosely enclosed by calyx, ovoid, 2–3 mm, 2/3–4/5 times as long as sepals.
8–35, black, suborbicular, slightly compressed, 0.7–0.8 mm, shiny, smooth.
5–7, dark brown to black, subglobose, slightly compressed, ca. 1 mm, shiny, smooth.
= 40, 44.
Arenaria lanuginosa
Arenaria livermorensis
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.)
Of conservation concern.
Arenaria livermorensis is known only from the Davis Mountains in the Trans-Pecos region of western Texas. It may be related to A. lycopodioides Willdenow ex Schlechtendal, a species found in the mountains of central Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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 |
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