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FNA | Family List | FNA Vol. 5 | Caryophyllaceae

24. Minuartia Loefling in C. Linnaeus, Sp. Pl. 1: 89. 1753. Gen. Pl. ed. 5, 39. 1754.

Sandwort [for J. Minuart, 1693-1768, Spanish botanist and pharmacist]

Richard K. Rabeler, Ronald L. Hartman, Frederick H. Utech

Alsinanthe (Fenzl ex Endlicher) Reichenbach; Alsinopsis Small; Lidia Á. Löve & D. Löve; Minuopsis W. A. Weber; Porsildia Á. Löve & D. Löve; Sabulina Reichenbach; Tryphane (Fenzl) Reichenbach; Wierzbickia Reichenbach

Herbs, annual, winter annual, or perennial, sometimes mat-forming. Taproots filiform to stout and woody, perennial plants often with branched caudex or with rhizomes or trailing stems. Stems ascending to erect or prostrate, simple or branched, ± terete. Leaves mostly connate proximally, petiolate (M. cumberlandensis, M. godfreyi proximal leaves) or sessile; blade 1-3-veined, sometimes obscurely so, filiform-linear to subulate, lanceolate or oblanceolate, rarely to ovate, herbaceous to succulent, apex blunt, rounded, or obtuse to acute, acuminate, or spinescent. Inflorescences terminal, open or seldom congested cymes or flowers solitary and terminal or axillary, rarely absent; bracts paired, herbaceous or scarious, rarely absent (M. pusilla, M. rossii). Pedicels erect to arcuate-spreading, rarely reflexed (M. drummondii) in fruit. Flowers: perianth and androecium perigynous; hypanthium usually disc-, occasionally dish- or cup-shaped; sepals 5, distinct, green (herbaceous portion purple in M. arctica, M. macrocarpa, and M. rossii), linear, lanceolate, or oblong to elliptic, ovate, or broadly ovate, 1.5-6(-9) mm, margins herbaceous or silvery and scarious, apex rounded or obtuse to acute, acuminate, or spinescent, sometimes hooded; petals 5 or rarely absent, white, rarely pink (M. biflora) or lilac (M. marcescens), clawed (M. glabra, M. groenlandica) or not, blade apex entire, emarginate, or notched; nectaries 5, at base of filaments opposite sepals, sometimes prominent and 2-lobed; stamens 10 (8-10 in M. godfreyi), arising from hypanthium; filaments distinct; staminodes absent; styles 3 (to 4 in M. cumberlandensis, M. godfreyi), filiform, 0.6-2.5 mm, glabrous proximally; stigmas 3 (to 4 in M. cumberlandensis, M. godfreyi), linear along adaxial surface of styles, minutely papillate (30×). Capsules ovoid to broadly ellipsoid or rarely globose, opening by 3 incurved or erect to recurved valves; carpophore absent or sometimes present. Seeds 1-25, reddish brown to brown or black (or rarely yellowish or purplish brown), spherical or suborbiculate to reniform or obliquely triangular, plump or variously compressed, smooth, reticulate, tuberculate, muriculate-papillate, or rarely with long marginal papillae (M. macrocarpa), marginal wing absent (present in M. douglasii), appendage absent. x = 7, 9, 10, 12, 13, 14, 15, 23.

Species ca. 175 (33 in the flora): temperate and arctic Northern Hemisphere, n Africa, Asia Minor.

The nectaries in Minuartia flowers are often enlarged (to 0.5 mm) and variously lobed; they may not be apparent in fruiting material, possibly due to resorption by the developing flower following pollination. The hypanthium varies from disc- to cup-shaped and ranges in size from less than 1 mm to 3 to 4 mm in diameter (measured on the curve if cup-shaped). The cup-shaped hypanthium is best developed in fruiting material of M. arctica, M. obtusiloba, and relatives.

Minuartia is the second largest genus of Caryophyllaceae in our flora. It is the largest that here includes strictly native taxa. Of the eight genera with ten or more species, only Eremogone also is represented solely by native species.

J. McNeill (1962) outlined an infrageneric classification of Minuartia that included four subgenera and 12 sections within subg. Minuartia; our 33 species would be distributed among seven of those 12 sections. While we follow McNeill (1962, 1980b) in recognizing Arenaria and Minuartia, we have chosen not to adopt his hierarchy formally. Some of his groups do appear to represent natural assemblages; others do not. One of the latter includes most of the Minuartia species native to the southeastern United States. McNeill (1962) placed these species in sect. Uninerviae (Fenzl) Mattfeld; J. Mattfeld (1922) divided them among three series within that section; Á. Löve and D. Löve (1975) segregated two species as the genus Porsildia. There has been no thorough subsequent study of the entire group that could further resolve the question. Molecular investigation of Minuartia (M. Nepokroeff et al. 2001) suggested that it is not monophyletic. One or more of the various segregate genera that have been proposed, originally based on morphological features, with some resurrected by Löve and Löve on cytological grounds, and that are now in use (e.g., Alsinanthe, Alsinopsis, Lidia, Minuopsis, Tryphane; W. A. Weber and R. C. Wittmann 1992) may prove to be supported by dna analysis as well.

Minuartia rossii, a densely pulvinate plant of moist arctic areas, may be difficult to identify in the key since flowers are often absent, especially in northern populations. Vegetative reproduction via easily detached axillary fascicles in the upper leaf axils is more common in these plants.


Mattfeld, J. 1922. Geographisch-genetische Untersuchungen über die Gattung Minuartia (L.) Hiern. Repert. Spec. Nov. Regni Veg. Beih. 15. McCormick, J. F., J. R. Bozeman, and S. A. Spongberg. 1971. A taxonomic revision of granite outcrop species of Minuartia (Arenaria). Brittonia 23: 149-160. McNeill, J. and I. J. Bassett. 1974. Pollen morphology and the infrageneric classification of Minuartia (Caryophyllaceae). Canad. J. Bot. 52: 1225-1231.

1 Plants annual, not cespitose, rarely mat-forming   (2)
+ Plants perennial, often cespitose, pulvinate, or mat-forming   (17)
2 (1) Sepal apices obtuse or merely acutish   (3)
+ Sepal apices acuminate to distinctly acute   (8)
3 (2) Pedicels stipitate-glandular   (4)
+ Pedicels glabrous   (6)
4 (3) Sepals 1-3-veined; seeds compressed, winged   10 Minuartia douglasii (in part)
+ Sepals obscurely veined; seeds somewhat compressed, not winged   (5)
5 (4) Leaf blades glabrous; seeds 0.7-0.8 mm, orbiculate, echinate; sc United States   11 Minuartia drummondii
+ Leaf blades stipitate-glandular; seeds 1.4-1.7 mm, suborbiculate, low-tuberculate; California, Oregon   16 Minuartia howellii (in part)
6 (3) Sepals 1- or 3-veined, 2.5-2.8 mm; petals not clawed; California, Oregon   4 Minuartia californica (in part)
+ Sepals obscurely veined, 1.5-4 mm; petals clawed or not; e United States   (7)
7 (6) Petals broadly obovate, clawed; seeds 0.5-0.8 mm, obliquely triangular with adaxial groove   13 Minuartia glabra
+ Petals oblanceolate to spatulate, not clawed; seeds 0.4-0.6 mm, suborbiculate, not grooved   32 Minuartia uniflora
8 (2) Sepals obscurely veined; leaves stipitate-glandular   16 Minuartia howellii (in part)
+ Sepals 1-5-veined, often prominently so; leaves glabrous or seldom stipitate-glandular   (9)
9 (8) Pedicels glabrous   (10)
+ Pedicels stipitate-glandular, sometimes sparsely so   (13)
10 (9) Leaves obscurely veined; petals 0.5-1 times as long as sepals or absent   25 Minuartia pusilla
+ Leaves 1-3-veined; petals 1-2.2(-3) times as long as sepals   (11)
11 (10) Leaves weakly 1-veined abaxially; sepals 1- or 3-veined, apex rounded to acute   4 Minuartia californica (in part)
+ Leaves 1-veined abaxially; sepals prominently 3-5-veined, apex acute to acuminate   (12)
12 (11) Sepals 3(-5)-veined; petals 1-1.5 times as long as sepals; capsules equaling or longer than sepals; California, Oregon   6 Minuartia cismontana
+ Sepals (3-)5-veined; petals 1.5-2.2(-3) times as long as sepals; capsules usually shorter than sepals; se and c United States   24 Minuartia patula (in part)
13 (9) Petal apices entire, w United States   (14)
+ Petal apices emarginate or notched; se and c United States   (15)
14 (13) Seeds 1.3-2 mm, winged   10 Minuartia douglasii (in part)
+ Seeds 0.4-0.6 mm, not winged   31 Minuartia tenella
15 (13) Flowering stems arising from slender wintering stems; inflorescences 3-5(-7)-flowered; petals oblong-spatulate   14 Minuartia godfreyi
+ Wintering stems absent; inflorescences 5-50+-flowered; petals obovate   (16)
16 (15) Sepals 3-veined, apex acute; leaf blades linear-lanceolate to oblanceolate, (0.6-)1.5-3.2 mm wide; seeds black, muriculate-papillate   21 Minuartia muscorum
+ Sepals (3- or) 5-veined, apex acute or acuminate; leaf blades linear, 0.5-1.5(-1.8) mm wide; seeds reddish brown to black, tuberculate   24 Minuartia patula (in part)
17 (1) Sepal apices broadly obtuse or rounded   (18)
+ Sepal apices acute to acuminate or spinescent   (31)
18 (17) Stems pubescent, at least distally, often stipitate-glandular   (19)
+ Stems glabrous   (24)
19 (18) Leaf blade apices acuminate-pungent; stems 10-30 cm; inflorescences 3-13-flowered   33 Minuartia yukonensis
+ Leaf blade apices rounded to truncate; stems 1-12 cm; inflorescences 1-5-flowered   (20)
20 (19) Leaf blades flat, obscurely 1- or 3-veined   (21)
+ Leaf blades 3-angled or rounded 3-angled, obscurely or prominently 1- or 3-veined   (22)
21 (20) Inflorescences with flowers solitary; capsules narrowly ellipsoid, 10-18 mm; seeds ringed with elongate papillae   18 Minuartia macrocarpa (in part)
+ Inflorescences 3-5-flowered; capsules broadly ellipsoid, 5.5 mm; seeds smooth or obscurely sculptured   3 Minuartia biflora (in part)
22 (20) Axillary leaves absent; leaf blades obscurely 1-veined; seeds 1.2-1.6 mm, brown, minutely tuberculate   1 Minuartia arctica
+ Axillary leaves present among vegetative leaves; leaf blades 1- or 3-veined abaxially; seeds 0.6-1.2 mm, brown or reddish tan, smooth or obscurely sculptured   (23)
23 (22) Capsules 6-10 mm; seeds 0.9-1.2 mm, brown   19 Minuartia marcescens
+ Capsules 3.5-6 mm; seeds 0.6-0.7 mm, reddish tan   23 Minuartia obtusiloba
24 (18) Stems 8-28 cm; inflorescences 5-12+-flowered; sepals broadly ovate   5 Minuartia caroliniana
+ Stems 1-10(-20) cm; inflorescences 1-5-flowered; sepals linear to ovate or obovate   (25)
25 (24) Petals with apex emarginate or notched, petals 1.4-2.2 times as long as sepals; inflorescences 2-5(-7)-flowered cymes or flowers solitary   (26)
+ Petals with apex entire, petals 0.8-2 times as long as sepals (sometimes absent); inflorescences with flowers solitary   (28)
26 (25) Pedicels stipitate-glandular   3 Minuartia biflora (in part)
+ Pedicels glabrous   (27)
27 (26) Leaf blades (10-)20-30(-40) × 1-3 mm, linear-oblanceolate to linear-spatulate; inflorescences 1(-3)-flowered   7 Minuartia cumberlandensis
+ Leaf blades 4-12(-15) × 0.5 mm, ± linear; inflorescences 3-5-flowered   15 Minuartia groenlandica
28 (25) Leaf blades 3-veined, often prominently so abaxially; capsules narrowly ellipsoid, 10-18 mm   18 Minuartia macrocarpa (in part)
+ Leaf blades 1-veined; capsules spherical or ellipsoid, 1.5-4 mm   (29)
29 (28) Stems 1-3 cm; sepals 1-veined   27 Minuartia rossii (in part)
+ Stems 3-15 cm; sepals 3-veined   (30)
30 (29) Sepals, linear to lanceolate; petals rudimentary or absent   2 Minuartia austromontana (in part)
+ Sepals, ovate to lanceolate; petals 0.8-1 times as long as sepals   12 Minuartia elegans (in part)
31 (17) Petals 2.5-3 times as long as sepals, apex shallowly notched   14 Minuartia godfreyi (in part)
+ Petals with apex entire, if slightly emarginate, then petals 0.7-0.9 times as long as sepals, or absent   (32)
32 (31) Pedicels stipitate-glandular   (33)
+ Pedicels glabrous   (37)
33 (32) Stems cespitose to mat-forming; taproot not woody, filiform to somewhat thickened, rhizomes or trailing stems absent; seeds 0.4-0.5 mm   28 Minuartia rubella
+ Stems mat-forming; taproot woody, stout; rhizomes, stolons, or trailing stems present; seeds 1.5-2.7 mm   (34)
34 (33) Plants densely stipitate-glandular throughout; w North America   22 Minuartia nuttallii
+ Plants sparsely stipitate-glandular on pedicels and sepals; California   (35)
35 (34) Petals 0.7-0.9 times as long as sepals; stems and leaves green   9 Minuartia decumbens
+ Petals 1.4-2.2 times as long as sepals; stems and leaves glaucous or gray-green   (36)
36 (35) Stems and leaves glaucous, proximal leaves longer than internodes   26 Minuartia rosei
+ Stems and leaves gray-green, proximal leaves often shorter than internodes   29 Minuartia stolonifera
37 (32) Petals 1.1-2 times as long as sepals   (38)
+ Petals 0.5-1 times as long as sepals, rudimentary or absent   (40)
38 (37) Leaf blades 1-4 mm, 3-angled, 1-veined; sepals 1-veined; high arctic   27 Minuartia rossii (in part)
+ Leaf blades 5-30 mm, flat to 3-angled, 1-3 veined; sepals 3-veined   (39)
39 (38) Leaf blades flat to navicular, apex blunt to pungent; inflorescences 5-30-flowered; Great Plains and east   20 Minuartia michauxii
+ Leaf blades navicular, apex rounded; inflorescences 1- or 2-5(-8)-flowered; Great Basin and Rocky Mountains   17 Minuartia macrantha (in part)
40 (37) Inflorescences with flowers solitary, terminal   (41)
+ Inflorescences with flowers solitary and terminal or often 2-5(-15)-flowered   (42)
41 (40) Sepals linear to lanceolate; petals rudimentary or absent   2 Minuartia austromontana (in part)
+ Sepals ovate to lanceolate; petals 0.8-1 times as long as sepals   12 Minuartia elegans (in part)
42 (40) Sepals 3.5-5 mm, to 5.5 mm in fruit; seeds 0.7-1 mm   17 Minuartia macrantha (in part)
+ Sepals (1.5-)2.5-3.2 mm, to 4 mm in fruit; seeds 0.4-0.6 mm. [43. Shifted to left margin.—Ed.]   (43)
43 (42) Inflorescences 7-15-flowered (rarely fewer); seeds dark brown to black, 0.5-0.6 mm   8 Minuartia dawsonensis
+ Inflorescences 1-3(-5)-flowered; seeds brown or reddish brown, 0.4-0.6 mm   30 Minuartia stricta

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