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birch-leaf mountain mahogany, California moutain-mahogany

Habit Shrubs or trees, 10–50(–80) dm, sparsely to moderately branched, young stems, leaves, pedicels, and hypanthia sericeous (hairs straight, antrorse, appressed, or ± ascending), or hirsute-pilose (hairs erect, straight), or ± villous (hairs wavy or wavy-crinkled), or hairs tightly coiled or 1/2 coiled, or 1/2 coiled at base and erect-ascending, wavy distally, 0.2–0.8(–1.3) mm.
Stems

long-shoot internodes 3–20(–55) mm, ± sparsely hairy, glabrescent; short shoots 3–30(–55) × 1–2.5 mm.

Leaves

persistent or ± drought-deciduous;

stipules (1.5–)3.5–6(–10) mm, 1.5–2.5 mm in s California;

petiole 1.5–9(–16) mm;

blade oblong-obovate, rhombic, suborbiculate to broadly ovate, rarely oblong-elliptic, (8–)12–50(–78) × (4–)8–35(–64) mm, membranous to coriaceous, base cuneate to rounded, rarely ± cordate, margins ± revolute or flat, dentate, serrate, or, in broader leaves, crenate in distal 1/5–3/4, apex rounded, sometimes acute, abaxial surface sericeous, pilose, villous, or with curled hairs on veins, areoles canescent or glabrous, adaxial sparsely hairy, sometimes glabrate.

Flowers

1–18 per short shoot;

hypanthial tubes sericeous, woolly, or villous or with coiled or spreading hairs;

hypanthial cups 2–4 × 4–7 mm;

sepals 5, broadly deltate, 1–2.5 mm, acute-acuminate;

stamens 20–61, anthers 1–1.5 mm, hirsute.

Achenes

7–11(–13.5) × 1.5–2.5(–2.9) mm; fruiting pedicels (1.5–)3–11(–21) mm;

hypanthial tubes (5–)7–13(–17) mm;

pedicel/tube ratio (15–)35–90(–126)%;

fruit awns 5–8.5(–12.5) cm, proximal setae 2.7–5 mm.

Cercocarpus betuloides

Distribution
from FNA
AZ; CA; OR; nw Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

The western, spring-flowering Cercocarpus betuloides in the broad sense, centered in California, is well supported by molecular data. A total of five taxa have been recognized in recent floras; molecular data provide no support for these taxa, but instead support recognition of a single inclusive taxon.

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

Key
1. Leaves, young stems, and hypanthial tubes appressed-sericeous or hypanthial tubes also with erect-ascending hairs (hairs not coiled); flowers 1–3(–10) per short shoot; transmontane s, c California, c Arizona, and sw Oregon.
var. betuloides
1. Leaves, young stems, and hypanthial tubes commonly with tightly coiled hairs (except in some insular plants where sericeous); flowers (1–)3–6(–18) per short shoot; cismontane s California
→ 2
2. Leaf blades sparsely to moderately hairy, subcoriaceous to coriaceous, margins serrate or dentate or crenate in distal 1/5–3/4; coastal s California and adjacent islands.
Cercocarpus betuloides var. blancheae
2. Leaf blades abaxially densely woolly, strongly coriaceous, margins (often strongly revolute, usually obscuring teeth), crenate, dentate-serrate in distal 1/2–3/4; sw Santa Catalina Island.
var. traskiae
Source FNA vol. 9, p. 333.
Parent taxa Rosaceae > subfam. Dryadoideae > tribe Dryadeae > Cercocarpus
Sibling taxa
C. breviflorus, C. ledifolius, C. montanus
Subordinate taxa
C. betuloides var. betuloides, C. betuloides var. traskiae
Name authority Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 427. (1840)
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