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Ross' sandwort

Habit Plants perennial, densely pulvinate to loosely cespitose. Herbs, winter annual, annual, biennial, or perennial; taprooted and/or rhizomatous, rarely with tuberous thickenings (Pseudostellaria).
Taproots

stout, woody.

Stems

ascending to spreading, green or often purple, 1–3 cm, glabrous, internodes of flowering stems 0.2–1 times as long as leaves.

prostrate to ascending or erect, simple or branched.

Leaves

overlapping, ± tightly (vegetative), ± evenly spaced proximally (cauline), connate-perfoliate proximally, with tight, herbaceous sheath 0.2–0.3 mm;

blade upwardly curved, green or often purple, keeled, prominently 1-veined abaxially, subulate, 3-angled, 1–4 × 0.5–0.7 mm, flexuous, margins rounded, herbaceous, smooth, apex green to purple, rounded, navicular, shiny, glabrous;

axillary leaves well developed.

opposite, connate proximally or not, often petiolate (basal leaves), not stipulate;

blade subulate or linear to spatulate, lanceolate, or broadly ovate, seldom succulent.

Inflorescences

solitary flowers, axillary or terminal (rarely present);

bracts absent.

terminal or axillary cymes, or flowers solitary;

bracts foliaceous or reduced, herbaceous to scarious (or rarely absent);

involucel bracteoles absent.

Pedicels

0.1–2 cm, glabrous.

present or rarely flowers sessile.

Flowers

hypanthium disc-shaped;

sepals 1-veined, oblong-ovate (herbaceous portion usually purple, oblong-ovate), 1.5–2.5 mm, not enlarging in fruit, apex often purple, obtuse to acuminate, navicular, not hooded, glabrous;

petals obovate to spatulate, 1.5–2 times as long as sepals, apex obtuse, entire.

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).

Fruits

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.

Capsules

on stipe ca. 0.1–0.2 mm, spheric, 1.5–2.5 mm, equaling sepals.

Seeds

brown, suborbiculate, compression unknown, ca. 0.6 mm, obscurely reticulate.

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).

x

= 6–15, 17–19, 23.

2n

= 58 (Russia), 60.

Minuartia rossii

Caryophyllaceae subfam. alsinoideae

Phenology Flowering spring–summer.
Habitat Wet, turfy, gravelly, or sandy calcareous barrens, high arctic, alpine tundra, heathlands
Elevation 0-500 m (0-1600 ft)
Distribution
from FNA
AK; NT; NU; YT; Greenland; Europe (Spitzbergen); Asia (Russian Far East)
[BONAP county map]
North-temperate regions; South America (Andean region); Europe (Mediterranean region); w Asia; c Asia (Himalayas, Mediterranean region); Africa (Mediterranean region)
Discussion

Minuartia rossii is the northernmost member of the M. rossii complex (S. J. Wolf et al. 1979; B. Maguire 1958), a pulvinate species of moist arctic areas. While specimens occasionally have many flowers, some specimens have few if any, instead reproducing via small axillary fascicles of leaves or short shoots in the upper leaf axils (see also Ö. Nilsson 2001).

(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.)

Source FNA vol. 5, p. 133. FNA vol. 5, p. 50. Authors: Richard K. Rabeler, Ronald L. Hartman.
Parent taxa Caryophyllaceae > subfam. Alsinoideae > Minuartia Caryophyllaceae
Sibling taxa
M. arctica, M. austromontana, M. biflora, M. californica, M. caroliniana, M. cismontana, M. cumberlandensis, M. dawsonensis, M. decumbens, M. douglasii, M. drummondii, M. elegans, M. glabra, M. godfreyi, M. groenlandica, M. howellii, M. macrantha, M. macrocarpa, M. marcescens, M. michauxii, M. muscorum, M. nuttallii, M. obtusiloba, M. patula, M. pusilla, M. rosei, M. rubella, M. stolonifera, M. stricta, M. tenella, M. uniflora, M. yukonensis
Subordinate taxa
Synonyms Arenaria rossii, Alsinanthe rossii, Alsinopsis rossii, Arenaria rossii var. apetala, M. orthotrichoides, M. rolfii, M. rossii var. orthotrichoides
Name authority (R. Brown ex Richardson) Graebner: in P. F. A. Ascherson et al., Syn. Mitteleur. Fl. 5(1): 772. (1918) Fenzl: in S. L. Endlicher, Gen. Pl. 13: 963. (1840)
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