Potentilla sect. Terminales
Potentilla argentea
hoary cinquefoil, potentille argentée, silver cinquefoil, silver-leaf cinquefoil, silvery cinquefoil
decumbent to erect, not flagelliform, not rooting at nodes, from centers of ephemeral basal rosettes, 1–6 dm, lengths (2–)3–5(–10) times basal or proximal cauline leaves.
mostly decumbent to ascending, 1–6 dm.
basal not in ranks;
cauline 2–9;
primary leaves usually palmate, sometimes ternate, proximal ones 2–14 cm;
petiole: long hairs loosely appressed to spreading, soft to weak, glands absent or sparse to common;
leaflets 5–7, at tip of leaf axis, ± overlapping or not, oblanceolate to obovate, margins flat or revolute, distal 1/2–3/4+ evenly to unevenly incised 1/3–3/4+ to midvein, teeth 2–10 per side, surfaces similar to strongly dissimilar, abaxial green to white, cottony and/or crisped hairs absent or sparse to dense, adaxial green, not glaucous, long hairs weak to stiff.
palmate.
2–9, proximal ones 2–7(–10) cm;
proximal petioles 1–4(–7) cm, long hairs absent or sparse, ± ascending, 1–2 mm, soft, short and crisped hairs absent or obscured, cottony hairs dense, glands absent or obscured;
leaflets 5(–7), central one ± oblanceolate, (0.5–)1–3 × 0.3–1(–1.3) cm, margins revolute, distal 1/2–2/3 evenly or unevenly incised 1/2–3/4+ to midvein, teeth 2–3 per side (more if lobed or secondarily toothed), surfaces strongly dissimilar, abaxial white, long hairs ± sparse (mostly on veins), 1–2 mm, weak, short and crisped hairs absent or obscured, cottony hairs dense, glands absent or obscured, adaxial long hairs absent or sparse to common, short or crisped hairs absent or sparse, cottony hairs absent, glands absent or sparse.
10–100+-flowered, cymose, ± open.
10–80-flowered.
usually straight in fruit, 0.3–1.5(–3) cm, proximal ± longer than distal.
0.3–1.5(–2) cm.
5-merous;
hypanthium 2–5 mm diam.;
petals yellow, obovate to cuneate-obcordate, (2–)2.5–7(–8) mm, slightly shorter to ± longer than sepals, apex rounded to truncate or retuse;
stamens ca. 20;
styles subapical, columnar-tapered, scarcely to strongly papillate-swollen in proximal 1/5–1/2, 0.6–1.2 mm.
epicalyx bractlets oblong to narrowly ovate, 1.5–3 × 0.7–1.2 mm, lengths 2/3–1 times sepals;
sepals 2–4.5 mm, apex ± acute;
petals (2–)2.5–4 × 1.5–3 mm;
filaments 0.8–1.5 mm, anthers 0.3–0.6(–0.8) mm;
carpels 30–60, styles 0.6–0.9 mm, often strongly papillate-swollen proximally.
smooth to rugose.
0.8–1.1 mm, smooth to lightly rugose.
= 14, 28, 35, 42, 56, 62 (Eurasia).
Potentilla sect. Terminales
Potentilla argentea
Species 20–30 (3 in the flora).
As summarized by A. Kurtto et al. (in J. Jalas et al. 1972+, vol. 13), the species comprising sect. Terminales (including sect. Argenteae) consist of both sexual and apomictic populations of various ploidy levels that can be subdivided into more or less consistent species. The three species adventive in North America are relatively distinct, representing only a subset of European variation. Collections of Potentilla inclinata and P. intermedia are sometimes confused; the former often has petals smaller than the European average, and anthers are often intermediate in size. The distribution of the two species in North America may need adjusting from what is presented here.
Another species complex, the Potentilla collina Wibel group (as addressed by A. Kurtto et al. in J. Jalas et al. 1972+, vol. 13), may be present in North America, at least as an occasional waif. The specimens underlying the citation of this species by P. A. Rydberg (1898, 1908d) are here identified as P. argentea (New York) and P. inclinata (Minnesota); however, variation of traits distinguishing members of sect. Terminales can be subtle and difficult to interpret out of their European context.
Potentilla intermedia is considered to be of hybrid origin involving P. argentea and P. norvegica; it appears to reproduce by both sexual and apomictic means. Some authors consider P. inclinata to be the hybrid derivative of P. argentea and P. recta (A. Kurtto et al. in J. Jalas et al. 1972+, vol. 13). The P. collina group is likewise thought to have a hybrid origin, involving members of sections Aureae and Terminales. Placement of these species in sect. Terminales is made on the basis of key morphologic characters.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The bright, silvery vestiture of the leaves quickly distinguishes Potentilla argentea from P. inclinata and P. intermedia. Although treated here as introduced, some (P. A. Rydberg 1898; P. A. Werner and J. D. Soule 1976) considered P. argentea to be probably native in eastern North America.
The Potentilla argentea species group is an amphi- or apomictic polyploid complex that has been the subject of numerous cytological, sexual, and molecular studies (for example, A. Müntzing and G. Müntzing 1945; A. Müntzing 1958; J. Paule et al. 2011). Taxonomic treatments have ranged from a highly polymorphic single species to an abundance of species, varieties, and forms (T. Wolf 1908). This treatment is at the conservative end of the spectrum. Some New England references (R. C. Bean et al. 1967; F. C. Seymour 1969) distinguish plants with densely white-hairy adaxial leaflet surfaces as var. pseudocalabra Th. Wolf, a name based on plants from southeastern Europe. Molecular analysis by Paule et al. supports the conclusion by Wolf that the variety consists of intermediates between P. argentea and P. calabra Tenore. The optimum taxonomic disposition of var. pseudocalabra, and whether any North American plants are properly included, remains to be determined.
Potentilla argentea has been reported as an active agent in treating cirrhosis of the liver (N. T. Starostenko and V. N. Starostenko 1971).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaflet surfaces strongly dissimilar, abaxial white, cottony hairs dense, distal 1/2–2/3 of margin incised 1/2–3/4+ to midvein, teeth 2–3 per side (more if lobed or secondarily toothed). | P. argentea |
1. Leaflet surfaces similar or ± dissimilar, abaxial green, grayish, or gray-green, cottony hairs absent, distal (1/2–)3/4+ of margin incised 1/3–2/3 to midvein, teeth 4–10 per side | → 2 |
2. Anthers (0.5–)0.8–1.2 mm; petals 4–7(–8) mm; leaflets grayish to gray-green abaxially, short or crisped hairs usually ± abundant, sometimes sparse, margins usually evenly incised; epicalyx bractlets: lengths ± 1 times sepals. | P. inclinata |
2. Anthers 0.3–0.5 mm; petals 3–5 mm; leaflets green to grayish green abaxially, short or crisped hairs ± sparse, margins usually unevenly, sometimes evenly, incised (often with 1–2 incisions nearly to midvein); epicalyx bractlets: lengths usually 2/3, sometimes 1, times sepals. | P. intermedia |
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