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oso manzanita

Mt. Tamalpais manzanita

Habit Shrubs, erect or mound-forming, 1–4 m; burl absent; bark of older stems persistent, gray, shredded, sometimes red, smooth; twigs sparsely short-hairy. Shrubs, erect, prostrate, or mound-forming, 0.1–2 m; burl absent; twigs densely white short-hairy.
Leaves

petiole to 2 mm;

blade dark green, ± shiny, ovate to orbiculate-ovate, 1.5–3 × 1.5–2.5 cm, base deeply lobed, (clasping), margins entire, plane, surfaces smooth, sparsely short-hairy or glabrous.

petiole 2–6 mm;

blade dark green, shiny, orbiculate-elliptic to elliptic, 1–2.5 × 1–1.5 cm, base rounded to cuneate, margins entire, plane, surfaces smooth, puberulent, glabrescent.

Inflorescences

racemes, simple or 1-branched;

immature inflorescence pendent, (branches compact, framed by bracts), axis 0.5–1 cm, 1+ mm diam., sparsely short-hairy;

bracts not appressed, leaflike, lanceolate to ovate, 4–8 mm, apex acute, surfaces glabrous.

panicles, 1–3-branched;

immature inflorescence pendent, (branches compact), axis 0.5–1.5 cm, 1+ mm diam., densely white short-hairy;

bracts tightly appressed, scalelike, ovate, 2–5 mm, apex acuminate, surfaces glabrous.

Pedicels

8–9 mm, glabrous.

3–6 mm, glabrous.

Flowers

corolla white, urceolate;

ovary glabrous.

corolla white, conic to urceolate;

ovary glabrous.

Fruits

depressed-globose, 5–8 mm diam., glabrous.

globose, 4–8 mm diam., glabrous.

Stones

distinct.

distinct.

2n

= 26.

Arctostaphylos osoensis

Arctostaphylos montana

Phenology Flowering winter–early spring.
Habitat Maritime chaparral on volcanic uplands
Elevation 0-200 m (0-700 ft)
Distribution
from FNA
CA
[BONAP county map]
from USDA
wc Calif
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Arctostaphylos osoensis is found in the volcanic hills east of Morro Bay, San Luis Obispo County.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Subspecies 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Fruits 6-8 mm diam.; plants mound-forming or erect; leaf blades orbiculate-elliptic to elliptic, 1-2.5 × 1-1.5 cm; young twigs white-tomentose.
subsp. montana
1. Fruits 4-5 mm diam.; plants prostrate; leaf blades orbiculate-elliptic, 1-2 × 1-1.5 cm; young twigs gray-tomentose.
subsp. ravenii
Source FNA vol. 8, p. 434. FNA vol. 8, p. 436.
Parent taxa Ericaceae > subfam. Arbutoideae > Arctostaphylos Ericaceae > subfam. Arbutoideae > Arctostaphylos
Sibling taxa
A. andersonii, A. auriculata, A. bakeri, A. canescens, A. catalinae, A. columbiana, A. confertiflora, A. crustacea, A. cruzensis, A. densiflora, A. edmundsii, A. franciscana, A. gabilanensis, A. glandulosa, A. glauca, A. glutinosa, A. hispidula, A. hookeri, A. hooveri, A. imbricata, A. insularis, A. klamathensis, A. luciana, A. malloryi, A. manzanita, A. mewukka, A. montana, A. montaraensis, A. montereyensis, A. morroensis, A. myrtifolia, A. nevadensis, A. nissenana, A. nortensis, A. nummularia, A. obispoensis, A. ohloneana, A. otayensis, A. pacifica, A. pajaroensis, A. pallida, A. parryana, A. patula, A. pechoensis, A. pilosula, A. pringlei, A. pumila, A. pungens, A. purissima, A. rainbowensis, A. refugioensis, A. regismontana, A. rudis, A. sensitiva, A. silvicola, A. stanfordiana, A. tomentosa, A. uva-ursi, A. virgata, A. viridissima, A. viscida
A. andersonii, A. auriculata, A. bakeri, A. canescens, A. catalinae, A. columbiana, A. confertiflora, A. crustacea, A. cruzensis, A. densiflora, A. edmundsii, A. franciscana, A. gabilanensis, A. glandulosa, A. glauca, A. glutinosa, A. hispidula, A. hookeri, A. hooveri, A. imbricata, A. insularis, A. klamathensis, A. luciana, A. malloryi, A. manzanita, A. mewukka, A. montaraensis, A. montereyensis, A. morroensis, A. myrtifolia, A. nevadensis, A. nissenana, A. nortensis, A. nummularia, A. obispoensis, A. ohloneana, A. osoensis, A. otayensis, A. pacifica, A. pajaroensis, A. pallida, A. parryana, A. patula, A. pechoensis, A. pilosula, A. pringlei, A. pumila, A. pungens, A. purissima, A. rainbowensis, A. refugioensis, A. regismontana, A. rudis, A. sensitiva, A. silvicola, A. stanfordiana, A. tomentosa, A. uva-ursi, A. virgata, A. viridissima, A. viscida
Subordinate taxa
A. montana subsp. montana, A. montana subsp. ravenii
Synonyms A. hookeri subsp. montana, A. pungens var. montana
Name authority P. V. Wells: Four Seasons 9(2): 45. 1992 , Eastwood: Proc. Calif. Acad. Sci., ser. 3, 1: 83. (1897)
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