Stellaria media
Stellaria porsildii
chickweed, common chickweed, common starwort, common stitchwort, mouron des oiseaux
Porsild's starwort
decumbent or ascending, diffusely branched, 4-sided, 5–40 cm, with single line of hairs along each internode.
erect, diffusely branched, rarely elongate and straggling, branched mainly at base, 4-sided, 9–20 cm, glabrous.
petiolate (proximal) or ± sessile (distal);
blade usually green, ovate to broadly elliptic, 0.5–4 cm × 2–20 mm, base round to cuneate, margins entire, apex acute or shortly acuminate, ± glabrous or ciliate at base.
sessile;
blade green, never glaucous, linear to linear-lanceolate, widest at or near middle, 2.7–3.5 cm × 2–3 mm, not succulent, base cuneate, margins entire, apex gradually acuminate, acute, glabrous with few cilia at base.
terminal, 5–many-flowered cymes;
bracts ovate and shortly acuminate to lanceolate-acute, 1–40 mm, herbaceous.
with flowers solitary, terminal or axillary in distal foliage leaves.
ascending, usually straight, deflexed at base in fruit, 3–40 mm, usually with line of hairs.
erect, 18–50 mm, glabrous.
2–5 mm diam.;
sepals 5, with obscure midrib, ovate-lanceolate, 4.5–5(–6) mm, margins narrow, scarious, apex obtuse, usually glandular-hairy;
petals absent or 5, 1–4 mm, shorter than to equaling sepals;
stamens 3–5(–8);
anthers red-violet;
styles 3, outwardly curved, becoming curled, 0.5–1 mm.
7–10 mm diam.;
sepals 5, midrib prominent, lateral veins obscure, ovate-lanceolate to lanceolate, 4–6 mm, margins narrow, membranous, apex acute, glabrous;
petals 5, 4–6 mm, equaling or slightly longer than sepals, blade apex deeply divided into 2 oblanceolate lobes;
stamens 10;
styles 3, ascending, curled at tip, 2–3 mm.
green to straw colored, ovoid-oblong, 3–5 mm, somewhat longer than sepals, apex obtuse, opening by 6 valves;
carpophore absent.
black, oblong, 6–8 mm, slightly longer than sepals, apex obtuse, opening by 6 valves;
carpophore absent.
reddish brown, broadly reniform to round, 0.9–1.3 mm diam., with obtuse, round, or flat-topped (broader than tall) tubercles.
dark brown, broadly ovate, 0.8–1 mm diam., shallowly tuberculate.
= 40, 42, 44.
= 26.
Stellaria media
Stellaria porsildii
Stellaria media, now a cosmopolitan weed, is a very polymorphic species, varying in size, habit, pubescence, petal length, stamen number, and seed size and surface detail.
The Stellaria media complex consists of three very similar and closely related species, S. media, S. neglecta, and S. pallida. They can almost always be distinguished by the characters given in the key, but in a few doubtful cases a chromosome count is desirable for positive identification. The problem arises from the considerable phenotypic variation which is displayed by S. media, and to a lesser extent by S. pallida. There is no evidence for gene exchange between these species. Stellaria pallida is autogamous and sometimes cleistogamous; S. media is both autogamous and occasionally cross-pollinated by flies; S. neglecta is usually cross-pollinated by flies but is self-compatible.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Stellaria porsildii is closely related to S. longipes and S. longifolia and tends to be intermediate between them, with somewhat larger, solitary flowers. Its leaves tend to be more like those of S. longifolia, but they lack the papillate-scabrid margins, and have a few long cilia at the base. It is postulated that the polyploid S. longipes complex arose through hybridization between S. porsildii and S. longifolia, both of which are diploid (C. C. Chinnappa 1992). The two species can be hybridized but the artificial hybrid is diploid.
Stellaria porsildii can be very difficult to distinguish from forms of S. longipes, and a confirmatory chromosome count is desirable, at least for records from new locations. The total absence of minute papillae on the stems and leaf margins distinguishes both species from S. longifolia. The presence of a few long cilia at the base of the leaves is a useful indication of S. porsildii, but such cilia often are present in S. longipes. Confirmatory characters for S. porsildii are the open, erect to straggling habit of the plant (never compact and cushion-forming), and the leaves, which are green (never glaucous), soft (not stiff or coriaceous), always narrowly linear-lanceolate, and tending to be widest near the center of the lamina (not lanceolate and widest at the base).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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