Thyme Leaved Sandwort

Variation in Arenaria serpyllifolia in the broad sense is treated in various ways. The two varieties recognized here have been treated also as subspecies (e.g., A. O. Chater and G. Halliday 1993) or species (e.g., M. N. Abuhadra 2000; B. Jonsell 2001). Jonsell admitted that accepting them as species is questionable; while the morphological differences are slight (see esp. Abuhadra), the ploidy-level difference (2n = 40 in var. serpyllifolia vs. 2n = 20 in var. tenuior) is important.

This species is used medicinally.

Plants annual. Taproots filiform. Stems 1-100+, erect to ascending or sprawling, green, 3-40+ cm; internodes terete to ellipsoid, 2-8 times as long as leaves, dull, retrorsely pubescent throughout, sometimes also stipitate-glandu-lar. Leaves often connate basally, with scarious or mostly herba-ceous sheath 0.2-0.3 mm, petiolate (proximal leaves) or usually sessile; petiole 1-4 mm; blade 3-5 veined, elliptic to broadly ovate or rarely orbiculate, 2-7 × 1-4 mm, herbaceous, margins flat, herbaceous, dull, ciliate especially proximally, apex acute to acuminate, pustulate, sparsely minutely pubescent or glabrous; axillary leaf clusters absent. Inflorescences terminal, open, leafy, 3-50+-flowered cymes. Pedicels erect or ascending in fruit, 1-12 mm, retrorsely pubescent. Flowers: sepals green, often prominently 3-veined, not keeled, lanceolate to ovate-lanceolate (herbaceous portion narrowly elliptic to broadly lanceolate), 2-3 mm, to 4 mm in fruit, apex narrowly acute to acuminate, ± minutely pustulate, stipitate-glandular; petals oblong, 0.6-2.7 mm, 5- 4 times as long as sepals, apex obtuse to rounded. Capsules loosely enclosed by calyx, ovoid to cylindric-ovoid, 3-3.5 mm, 5-1 5 times as long as sepals. Seeds 10-15, ashy black, reniform, plump, 0.4-0.6 mm, not shiny, with low-elongate, prominent tubercules.

Herbs annual or biennial. Principal roots slender, with numerous smaller branches. Stems caespitose, erect or diffuse, 10--30 cm, densely white villous. Leaves sessile; leaf blade ovate, 4--12 × 3--7 mm, both surfaces glabrous or sparsely villous, 3-veined abaxially, base attenuate, margin ciliate, apex acute; proximal cauline leaves larger, distal ones smaller. Cymes many flowered; bracts ovate, 3--7 mm, herbaceous, usually densely villous. Pedicel slender, ca. 1 cm, densely villous or glandular pubescent. Sepals 5, lanceolate, 3--4 mm, villous abaxially, veins 3, impressed, margin membranous, apex acute. Petals 5, white, obovate, 1/3--1/2 as long as sepals, apex obtuse. Stamens 10, shorter than sepals. Ovary ovoid. Styles 3, linear. Capsule ovoid, equaling persistent sepals. Seeds pale brown, reniform, small, tuberculate with raised papillae. Fl. Jun--Aug, fr. Aug--Sep.

Europe, C. Asia, temperate Asia.

Widespread in China [N Africa, Asia, Australia, Europe, North America].

900-2900 m

Mountain grassland slopes, sandy or stony barrens, fields, gardens; 600--4000 m.

Arenaria leptoclados Gussone; A. petiolata Hayata.