Horkelia marinensis |
Rosaceae tribe Potentilleae |
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Point Reyes horkelia |
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Habit | Plants matted, green to grayish. | Herbs, perennial, rarely annual or biennial, shrubs, or subshrubs; unarmed. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | ± decumbent to ascending, 1–3.5(–4.5) dm, hairs spreading to ascending. |
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Leaves | alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos); stipules persistent (absent in Chamaerhodos), adnate to petiole; venation pinnate or palmate. |
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Basal leaves | ± planar to nearly cylindric, 4–12(–15) × 1–2.5(–3) cm; stipules entire or basally lobed; leaflets 5–10(–12) per side, ± overlapping especially distally, cuneate, 7–12 × 5–10 mm, nearly as wide as long, divided 1/3–1/2 to midrib into (3–)5–10 acute to obtuse teeth, villous. |
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Cauline leaves | 3–5. |
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Inflorescences | usually congested, flowers usually arranged in dense corymbiform clusters. |
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Pedicels | 1–6 mm. |
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Flowers | 10–15 mm diam.; epicalyx bractlets lanceolate, 2.5–4.5 × 1 mm, ± 2/3 length of sepals, entire; hypanthium 1.2–1.5 × 4–5 mm, less than 1/2 as deep as wide, interior pilose; sepals ± reflexed, lanceolate, 3–6 mm; petals narrowly oblanceolate to narrowly oblong, 4–7 × 2 mm, apex obtuse to rounded, rarely truncate; filaments 1–2.8 × 0.2–0.6 mm, anthers 0.6–0.9 mm; carpels 20–30; styles 2–4 mm. |
perianth and androecium perigynous; epicalyx bractlets present, sometimes absent; hypanthium usually patelliform, cupulate, or campanulate, sometimes turbinate, saucer-shaped, flat-bottomed, or subglobose to ellipsoid or ovoid; torus flat to conic or turbinate, enlarged (absent or reduced in Alchemilla, Aphanes, and Chamaerhodos); carpels 1–260, styles basal or lateral to subterminal, distinct; ovules 1(or 2), basal. |
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Fruits | aggregated achenes (achenes in Alchemilla and Aphanes); torus sometimes fleshy; styles deciduous or persistent, not elongate. |
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Achenes | brown, 1.5–2 mm, smooth to slightly rugose. |
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2n | = 56. |
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Horkelia marinensis |
Rosaceae tribe Potentilleae |
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Phenology | Flowering summer. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Sandy coastal flats, stabilized dunes | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 0–800 m (0–2600 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
CA
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North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Pacific Islands; Australia |
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Discussion | Of conservation concern. Horkelia marinensis occurs in three population clusters along the coast of California: near Fort Bragg and Rockport in Mendocino County, on Point Reyes Peninsula in Marin County, and from Santa Cruz and (historically) San Mateo counties. The last population cluster has often been confused with H. cuneata var. sericea; plants of it have more deeply and apically toothed, cuneate leaflets and longer, silkier hairs. It is also the basis for the attribution by J. H. Thomas (1961) of H. rydbergii (as H. bolanderi subsp. parryi) to the Santa Cruz Mountains. The three population clusters differ somewhat in vestiture, evident glandularity, and leaflet shape and size; further studies may indicate that varietal status is justified. References to H. marinensis in Sonoma County (M. G. Barbour 1970) are based on specimens of Acaena pinnatifida var. californica; reports from southern Mendocino County (G. L. Smith and C. R. Wheeler 1990–1991) are based on misidentifications of H. californica and H. tenuiloba. Horkelia marinensis is by far the most aromatic member of the genus; the odor, which has been compared to that of a beehive, often can be perceived even before the plants are located, especially on sunny days. Plants do relatively well in cultivation, forming spreading mats with flowers that are strongly attractive to both native bees and honeybees. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 14–22, species ca. 860 (14 genera, 189 species, including 1 hybrid, in the flora area). The base chromosome number for Potentilleae is mostly x = 7 (8 in Alchemilla and Aphanes; 14 in Comarum). Variation in the number of genera recognized in Potentilleae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of Potentilla and segregates here (see 9. Ivesia and 8. Potentilla for discussion). In the former, Duchesnea, Horkelia, Horkeliella, and Ivesia are included within Potentilla. Likewise, Aphanes is included within Alchemilla by Potter et al. while it is kept distinct here. Potentilla and its segregates and Fragaria are host to Phragmidium rusts, but not the other genera of the tribe. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 9, p. 253. | FNA vol. 9, p. 119. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Horkelia | Rosaceae > subfam. Rosoideae | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | H. bolanderi var. marinensis, Potentilla kelloggii var. marinensis, P. marinensis | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Elmer) Crum: Lloydia 1: 91. (1939) | Sweet: Brit. Fl. Gard. 2: sub plate 124. (1825) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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