Arenaria lanuginosa
Arenaria paludicola
spreading sandwort
marsh sandwort, swamp sandwort
filiform to moderately thickened;
rhizomes often present, slender, 2–15+ cm.
filiform;
rhizomes slender, 15+ cm.
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.
5–15, weakly erect, green, 25–90 cm;
internodes angular to grooved, 2/3–3 times as long as leaves, shiny, glabrous except for fine hairs at nodes.
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 scarious sheath 0.2–0.5 mm, sessile;
blade 1-veined (vein prominent abaxially), linear to linear-lanceolate, 20–55 × 2–7 mm, herbaceous to subsucculent, margins ± flat, scarious, shiny, ciliate, apex acute or acuminate to cuspidate, sometimes pustulate, sparsely pubescent on adaxial surface;
axillary leaf clusters absent.
axillary, solitary flowers or in proliferating, mostly terminal, leafy, 1–80+-flowered cymes.
axillary, solitary flowers.
erect to ascending (often arcuately so), or straight to widely divergent, often hooked distally in fruit, 2–40 mm, retrorsely pubescent.
reflexed in fruit, 20–50 mm, glabrous.
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, obscurely 1-veined, not keeled, broadly elliptic (herbaceous portion narrowly elliptic), 2.8–3.5 mm, to ca. 4 mm in fruit, apex obtuse to rounded, not pustulate, minutely ciliate basally;
petals ovate, 5–6 mm, 11/2–2 times as long as sepals, apex rounded.
± loosely to tightly enclosed by calyx, ovoid, 3–6 mm, 4/5–11/2 times as long as sepals.
tightly enclosed by calyx, ovoid, 4 mm, ca. equaling sepals.
8–35, black, suborbicular, slightly compressed, 0.7–0.8 mm, shiny, smooth.
15–20, dark brown, reniform, compressed, 0.8–0.9 mm, shiny, smooth.
= 40, 44.
Arenaria lanuginosa
Arenaria paludicola
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 paludicola is federally listed as endangered, and now is known only from a few sites in San Luis Obispo County; urban development and resultant habitat conversion have impacted it significantly. Historical collections of A. paludicola are known from other areas of the California coast and from Washington.
Arenaria paludicola occurs also in Mexico, where it grows (and is sometimes confused) with A. bourgaei Hemsley in lakes and wet areas above 2000 meters; the relationship of these species to each other and to A. lanuginosa requires study.
(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 |
CalFlora
LA Plants
WildflowerSearch
iNaturalist
USDA Plants Database
WA
Flora NW
PNW Herbaria
