Flora of North America species comparison

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Frangula californica

Frangula

California buckthorn, California coffee berry, coffeeberry

buckthorn, coffee berry
Habit Shrubs, 0.5–5 m. Stems red to gray or brown, glabrous or hairy. Shrubs or trees, unarmed; bud scales absent, buds hairy.
Leaves

usually persistent, rarely deciduous;

petiole 3–10 mm;

blade bright green to green, gray-green, yellowish green, or yellow abaxially, dark green to yellowish green or greenish white adaxially, not glaucous, ovate, elliptic, or oblong-elliptic, 2–10 cm, distinctly coriaceous, base cuneate to rounded or subcordate, margins entire or serrate, serrulate, or dentate-serrulate, apex acute or acuminate to obtuse, rounded, or truncate, abaxial surface glabrate or densely and closely white stellate-hairy, adaxial surface glabrous, glabrate, or sparsely hirsutulous;

secondary veins 7–11(–12) pairs.

usually deciduous, sometimes persistent, alternate [rarely opposite], rarely fascicled on short shoots;

blade not gland-dotted; pinnately veined, secondary veins nearly straight, parallel.
Inflorescences

umbels, pedunculate, 5–60-flowered.

axillary, within foliage, umbels or fascicles, or flowers solitary;

peduncles and pedicels not fleshy in fruit.
Pedicels

10–20 mm.

present.
Flowers

bisexual;

hypanthium cup-shaped, 1–3 mm wide, usually circumscissile far below sepal bases, rarely not circumscissile;

sepals (rarely 4–)5, usually ± erect, sometimes spreading, yellowish to green or white, ovate-triangular, fleshy, keeled adaxially;

petals (rarely 4–)5, yellowish, hooded, broadly obovate to obcordate, clawed;

nectary thin, lining hypanthium;

stamens (rarely 4–)5;

ovary superior, (2–)3-locular;

style 1.
Fruits

drupes;

stones 2–3(–4), indehiscent but open at base.
Drupes

black, globose or slightly elongate, 10–15 mm;

stones 2–3.

Seeds

obovoid to lenticular, with cartilaginous beak protruding through opening in stone, not furrowed.
Stigmas

2–3-parted.

x

= 20–26.

Frangula californica

Frangula
Distribution
from FNA
AZ; CA; NM; NV; OR; nw Mexico [Introduced in Pacific Islands (Hawaii)]
[WildflowerSearch map]
[BONAP county map]
from USDA
North America; Mexico; Central America; South America; West Indies; Europe; e Asia; n Africa
[BONAP county map]
Discussion

Subspecies 6 (6 in the flora).

Frangula californica grows throughout most of California, and the subspecies are more or less separated geographically, but intermediates exist among all the subspecies except subsp. ursina (C. B. Wolf 1938). In California, subsp. ursina occurs only in eastern San Bernardino County. Subspecies californica is the most coastal, growing from the western Klamath Mountains south to the Agua Tibia Mountain in southern California. Subspecies occidentalis is characteristic of mafic and ultramafic substrates in northwest California; plants on other substrates approach subsp. californica, but leaf blades are equally green (not yellow-green) on both surfaces. Wolf reported that a form of R. californica found abundantly from the San Francisco Bay region to Santa Barbara County has leaves that are whitened beneath, but the hairs are much shorter than in subsp. tomentella. Plants in Los Angeles and Orange counties have leaf blades with sparse (not dense) tomentum and a few long hairs beneath as in subsp. cuspidata. Intermediates between subspp. crassifolia and tomentella are rare in northern California, but many plants in San Diego County that Wolf considered subsp. tomentella have narrowly to broadly elliptic leaf blades, thus resembling subsp. crassifolia in the Inner Coast Range.

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

Species ca. 50 (7 in the flora).

The difference between Frangula and Rhamnus has long been recognized, but treatments in taxonomic rank have been inconsistent. Frangula was treated within Rhamnus by M. C. Johnston and L. A. Johnston (1978), who noted that Frangula and Rhamnus are more closely related to each other than to other taxa. This observation has been corroborated by molecular studies that show them as sister taxa (J. E. Richardson et al. 2000; K. Bolmgren and B. Oxelman 2004). Frangula was also included within Rhamnus by D. Medan and C. Schirarend (2004) and by Chen Y. L. and C. Schirarend (2007), but various other recent treatments, as here, have maintained them as separate genera, emphasizing the differences outlined above in couplet 13 of the key to genera.

The key to species emphasizes geography as a primary character, reflecting the close similarities among the species and allowing morphological contrasts between sympatric taxa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blade surfaces glabrous or abaxial slightly puberulent; drupe stones 2–3.
→ 2
2. Leaf blades bright green or yellow abaxially, dark green adaxially; drupe stones 2.
subsp. californica
2. Leaf blades yellowish green on both surfaces; drupe stones 3.
subsp. occidentalis
1. Leaf blade abaxial surface white stellate-hairy, sometimes with intermixed simple, erect hairs, adaxial surface glabrous, glabrate, sparsely hirsutulous, or sparsely stellate-hairy; drupe stones 2.
→ 3
3. Leaf blade abaxial surfaces without simple, erect hairs.
→ 4
4. Leaf blades narrowly elliptic, green and glossy adaxially, abaxial surfaces densely and closely white stellate-hairy, adaxial surfaces glabrous.
subsp. tomentella
4. Leaf blades broadly elliptic to oblong-elliptic, green to gray-green adaxially, both surfaces white stellate-hairy, sparsely so adaxially.
subsp. crassifolia
3. Leaf blade abaxial surfaces with simple, erect hairs, at least along veins.
→ 5
5. Leaf blade apices abruptly acuminate to acute, margins sharply serrate to dentate-serrulate, sometimes strongly revolute.
subsp. cuspidata
5. Leaf blade apices acute to rounded, margins entire or serrulate to serrate, flat to slightly revolute.
subsp. ursina
1. Leaves persistent, semideciduous, or deciduous, blades distinctly coriaceous.
→ 2
2. Leaves persistent; drupes 10–15 mm.
F. californica
2. Leaves semideciduous or deciduous; drupes 5–10 mm.
→ 3
3. Leaf blades glaucous adaxially when fresh; Plumas County, California.
F. purshiana
3. Leaf blades not glaucous adaxially; Arizona, Colorado, Nevada, Utah.
F. obovata
1. Leaves deciduous, blades herbaceous to subcoriaceous.
→ 4
4. Eastern North America, as far west as Manitoba, Nebraska, and central Texas.
→ 5
5. Inflorescences umbels, pedunculate; drupes 8–10 mm; leaf blades oblong to elliptic or obovate-elliptic, margins serrulate to crenulate to nearly entire; drupe stones 3.
F. caroliniana
5. Inflorescences fascicles, sessile; drupes 6–8 mm; leaf blades broadly elliptic-obovate to broadly elliptic or broadly oblong, margins entire; drupe stones 2(–3).
F. alnus
4. Western North America, as far east as Colorado, New Mexico, trans-Pecos Texas, and Wyoming.
→ 6
6. Inflorescences fascicles, sessile.
F. alnus
6. Inflorescences umbels, pedunculate.
→ 7
7. British Columbia, California, Idaho, Montana, w Nevada, Oregon, Washington.
→ 8
8. Leaf blades 1.5–8.5 cm; drupe stones 2(–3); inflorescences (2–)4–15-flowered; California, Nevada, Oregon.
F. rubra
8. Leaf blades 6–15 cm; drupes stones 3; inflorescences 10–25-flowered; British Columbia; California, Idaho, Montana, Nevada, Oregon, Washington.
F. purshiana
7. Arizona, Colorado, s Nevada, New Mexico, Texas, Utah.
→ 9
9. Leaf blades elliptic to oblong, elliptic-ovate, or narrowly ovate, 1.6–2.6(–2.9) times longer than wide, ± herbaceous, secondary veins (8–)9–13 pairs; se Arizona, New Mexico, Texas.
F. betulifolia
9. Leaf blades obovate to oblong-obovate or oblong, 1.2–1.8(–2.5) times longer than wide, subcoriaceous, secondary veins (5–)6–8(–9) pairs; n Arizona, Colorado, Nevada, Utah.
F. obovata
Source FNA vol. 12, p. 53. FNA vol. 12, p. 52. Authors: John O. Sawyer†, Guy L. Nesom.
Parent taxa Rhamnaceae > Frangula Rhamnaceae
Sibling taxa
F. alnus, F. betulifolia, F. caroliniana, F. obovata, F. purshiana, F. rubra
Subordinate taxa
F. californica subsp. californica, F. californica subsp. crassifolia, F. californica subsp. cuspidata, F. californica subsp. occidentalis, F. californica subsp. tomentella, F. californica subsp. ursina
F. alnus, F. betulifolia, F. californica, F. caroliniana, F. obovata, F. purshiana, F. rubra
Synonyms Rhamnus californica, R. purshiana var. californica Rhamnus section frangula, Rhamnus subg. frangula
Name authority (Eschscholtz) A. Gray: Gen. Amer. Bor. 2: 178. (1849) Miller: Gard. Dict. Abr. ed. 4, vol. 1. (1754)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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