Cercocarpus breviflorus
Cercocarpus betuloides
desert mountain-mahogany, eastern mountain-mahogany, hairy mountain-mahogany
birch-leaf mountain mahogany, California moutain-mahogany
long-shoot internodes (3–)7–20(–37) mm, sericeous, pilose-hirsute or villous, glabrate; short shoots 5–60(–140) × 1.5–2.5 mm.
long-shoot internodes 3–20(–55) mm, ± sparsely hairy, glabrescent; short shoots 3–30(–55) × 1–2.5 mm.
persistent or drought-deciduous;
stipules 1.5–2.5(–3) mm;
petiole (1–)2–5(-9) mm;
blade narrowly oblanceolate, oblong-oblanceolate, oblong-elliptic, narrowly obovate to obovate, sometimes ovate, (3–)7–35(–52) × (1.3–)4–15(–28) mm, coriaceous to subcoriaceous, base narrowly to broadly cuneate, margins serrulate to crenate in distal 1/2–1/3, teeth acute-apiculate, antrorse or proximal divergent in large leaves, or smaller blades entire, apex rounded to apiculate, abaxial surface sericeous, villous, or hirsute on veins, areoles canescent, rarely glabrous, adaxial moderately sericeous, hirsute, or villous.
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.
1–3(–7) per short shoot;
hypanthial tubes sericeous, hirsute-pilose to villous;
hypanthial cups 1.5–2.5 × 2.5–4 mm;
sepals 5, narrowly deltate, 1–2 mm, acute;
stamens (15–)20–40, anthers 0.6–1.2 mm, hirsute.
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.
6–9(–10.7) × 1.3–2 mm; fruiting pedicels (1–)2–5(–11.3) mm;
hypanthial tubes (4–)6–9(–10.2) mm;
pedicel/tube ratio (18–)30–50(–135)%;
fruit awns (2.5–)3.5–5(–7.2) cm, proximal setae 1.5–2.7 mm.
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 breviflorus
Cercocarpus betuloides
Cercocarpus breviflorus grows in the mountains of north-central Arizona, south-central New Mexico, and central and trans-Pecos Texas and in Mexico, over a 2000 km range. It has smaller flowers and shorter fruiting pedicels, hypanthial tubes, and stipules than C. betuloides. Flowering occurs after summer rains, providing reproductive isolation from C. betuloides.
In the mountains from east-central Arizona into north-central New Mexico, about 70–80% of plants of Cercocarpus breviflorus have pilose-hirsute to villous vestiture, and leaves tend to be thinner and more obovate with five to seven teeth in the rounded apical margins. In more arid montane regions of southern New Mexico, trans-Pecos Texas, and Mexico, leaves are more commonly sericeous (70%), often smaller, more coriaceous, with fewer teeth, in extreme being entire with a single terminal tooth. In strongly arid conditions, plants are smaller, more intricately branched, and thorny. These differences appear suitable for taxonomic recognition; a broad zone of intergradation occurs in southeastern Arizona and south-central New Mexico.
In the Big Bend region and Hill County of Texas and in the Chihuahuan Desert and mountains of eastern Mexico, plants of Cercocarpus breviflorus in more mesic chaparral habitats on north-facing slopes and drainages are taller with larger, sericeous, toothed leaves, often with the proximal teeth divergent. These plants blend completely into smaller-leaved plants in more arid sites on the same mountains. As in the C. betuloides complex, there are also plants with glabrous abaxial areoles.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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 |
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