Myosoton aquaticum
Caryophyllaceae subfam. alsinoideae
giant-chickweed, water-chickweed
10–100 cm, minutely glandular-pilose distally.
prostrate to ascending or erect, simple or branched.
blades 2–3.5(–8.5) × 1–2(–4.4) cm.
opposite, connate proximally or not, often petiolate (basal leaves), not stipulate;
blade subulate or linear to spatulate, lanceolate, or broadly ovate, seldom succulent.
terminal or axillary cymes, or flowers solitary;
bracts foliaceous or reduced, herbaceous to scarious (or rarely absent);
involucel bracteoles absent.
1–2(–3) cm, minutely glandular-pilose.
present or rarely flowers sessile.
sepals 4–6 mm, to 9 mm in fruit;
petals 4–7 mm, mostly exceeding sepals.
bisexual or seldom unisexual, sometimes inconspicuous;
perianth and androecium hypogynous or perigynous, often slightly;
hypanthium cup-, dish-, or disc-shaped;
sepals (4–)5, distinct or seldom connate basally, sometimes hooded, not awned;
petals absent or (1–)4–5, usually white, sometimes translucent, yellowish white, pink, or brownish, seldom clawed, auricles absent, coronal appendages absent, blade apex entire or 2-fid, sometimes jagged or emarginate, rarely laciniate;
stamens absent or (1–)5(–10), in 1 or 2 whorls, arising from base of ovary, a nectariferous disc, or sometimes the hypanthium or hypanthium rim;
staminodes absent or 1–5(–8);
ovary 1- or rarely 3-locular (Wilhelmsia);
styles (2–)3–5(–6), distinct;
stigmas (2–)3–5(–6).
capsules, or rarely utricles (Scleranthus), opening by (2–)3–6, occasionally 8 or 10 valves or (3 or) 6–10 teeth;
carpophore present or often absent.
5–10 mm, usually slightly exceeding calyx.
1–60+, yellowish or tan to dark red or often brown or black, usually reniform or triangular to circular and laterally compressed or ovoid to globose, rarely oblong and dorsiventrally compressed (Holosteum);
embryo usually peripheral and curved, rarely central and straight (Holosteum).
= 6–15, 17–19, 23.
= 20(?) (Asia), 28 (Europe, Asia), 29 (Europe).
Myosoton aquaticum
Caryophyllaceae subfam. alsinoideae
Reports of Myosoton aquaticum from Louisiana appear to be based on misidentified specimens of Stellaria cuspidata Willdenow ex Schlechtendal subsp. prostrata (Baldwin) J. K. Morton.
Although occurring over a wide area, Myosoton aquaticum is often noted as rare or occasional in particular states or provinces. Very few collections of this species from the flora area were made prior to 1900; two of the first gatherings were from port areas (Baltimore, Maryland, and as a ballast plant in Philadelphia, Pennsylvania, in 1877). Its presence outside the Japanese Pavillion at the Philadelphia Centennial Grounds in 1878 (Scribner 50 and 51, MO) suggests an escape from an intentional introduction.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 30, species ca. 1040 (16 genera, 137 species in the flora).
Alsinoideae, often considered basal in the family and the least specialized, is in some ways the most heterogeneous of the subfamilies. Members of its largest tribe (Alsineae) share the following characteristics: stipules absent, sepals free or at most basally connate, and capsular fruits. Indehiscent fruits, relatively short hypanthia, and other floral reductions occur in varying combinations in the approximately 30 species placed in four other tribes. A broad molecular survey of Alsinoideae has revealed two major lineages and lack of support for the existing tribal circumscriptions (M. Nepokroeff et al. 2002). About three-fourths of the species are members of Arenaria, Cerastium, Minuartia, and Stellaria.
Attempts have been made to move Scleranthus (fruit a utricle surrounded by an enlarged hypanthium) from Alsinoideae to either Paronychioideae (J. Hutchinson 1973, as Illecebraceae) or Scleranthaceae (A. Takhtajan 1997). Recent molecular and morphological studies by R. D. Smissen et. al. (2002, 2003) supported its retention in the Alsinoideae.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
OR, 
WA - Local Web sites:
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
