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beechleaf frangula, birchleaf buckthorn

pearleaf buckthorn

Habit Shrubs or small trees, 1–4 m. Stems brown to gray-brown, glabrous or pubescent. Shrubs, 1–2.5 m. Stems red to brown or gray-brown, glabrous or pubescent.
Leaves

deciduous;

petiole (2–)5–16 mm;

blade yellowish green abaxially, green adaxially, elliptic to oblong, elliptic-ovate or narrowly ovate, (4–)4.5–10 x (2–)2.5–5.5 cm, 1.6–2.6(–2.9) times longer than wide, ± herbaceous, base obtuse to truncate or rounded, margins serrate to subcrenate, apex usually acute to obtuse, sometimes slightly acuminate, both surfaces hirtellous, glabrescent;

secondary veins (8–)9–13 pairs.

deciduous;

petiole 5–14 mm;

blade usually equally green on both surfaces, not glaucous, obovate to oblong-obovate or oblong, (4–)5–9 × 3.2–6 cm, 1.2–1.8(–2.5) times longer than wide, subcoriaceous to distinctly coriaceous, base truncate to subcordate, margins serrulate to nearly entire, apex obtuse to truncate or rounded, both surfaces minutely puberulous to hirtellous, glabrescent;

secondary veins (5–)6–8(–9) pairs.

Inflorescences

umbels, pedunculate, 2–20(–38)-flowered.

umbels, pedunculate, 2–12-flowered.

Pedicels

3–7 mm.

3–10 mm.

Drupes

black, globose, 5–10 mm;

stones (2–)3(–4).

black, globose, 5–8 mm;

stones 3.

Stigmas

3-lobed.

3-lobed.

Frangula betulifolia

Frangula obovata

Phenology Flowering Apr–Jun. Flowering Apr–Jun.
Habitat Moist canyons, stream banks, rocky slopes, cliff bases, ledges, ridges, roadsides, deciduous, coniferous, and mixed woodlands. Hanging gardens, cliff faces, talus, canyon bottoms, seepage below cliffs, stream and creek banks.
Elevation 900–2800 m. (3000–9200 ft.) 1300–2400 m. (4300–7900 ft.)
Distribution
from FNA
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, Sonora, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; NV; UT
[BONAP county map]
Discussion

In the flora area, Frangula betulifolia is found in southeastern Arizona, the southern two-thirds of New Mexico, and trans-Pecos Texas. It and F. obovata are allopatric and morphologically distinct. C. B. Wolf (1938) considered a collection from Cochise County in southeastern Arizona, named as Rhamnus blumeri (Frangula ×blumeri), to be a hybrid between Frangula betulifolia and F. californica var. ursina; see the discussion of the latter taxon for more information.

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

Frangula obovata is known from Clark County, Nevada, across northern Arizona and southern Utah to southwestern Colorado; its distribution does not overlap that of F. betulifolia.

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

Source FNA vol. 12, p. 58. FNA vol. 12, p. 58.
Parent taxa Rhamnaceae > Frangula Rhamnaceae > Frangula
Sibling taxa
F. alnus, F. californica, F. caroliniana, F. obovata, F. purshiana, F. rubra
F. alnus, F. betulifolia, F. californica, F. caroliniana, F. purshiana, F. rubra
Synonyms Rhamnus betulifolia Rhamnus betulifolia var. obovata, F. betulifolia subsp. obovata
Name authority (Greene) Grubov: Trudy Bot. Inst. Akad. Nauk S.S.S.R., Ser. 1, Fl. Sist. Vyssh. Rast. 8: 268. (1949) (Kearney & Peebles) G. L. Nesom & J. O. Sawyer: Phytologia 91: 302. (2009)
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