Flora of North America species comparison

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Alnus oblongifolia

Alnus rhombifolia

aliso (Mexico), Arizona alder, New Mexican alder, oblong leaf alder

California alder, white alder
Habit Trees, to 30 m; trunks often several, crowns spreading. Trees, to 35 m; trunks often several, crowns spreading, open.
Bark

dark gray, smooth, becoming blackish and breaking into shallow vertical plates in age;

lenticels inconspicuous.

light gray, smooth, becoming darker and breaking into scales in age;

lenticels inconspicuous.
Leaf

blade narrowly ovate or lanceolate to narrowly elliptic, 5–9 × 3–6 cm, leathery, base narrowly to broadly cuneate or narrowly rounded, margins flat, sharply and coarsely doubly serrate, rarely evenly and densely short-serrate, major teeth sharp, acuminate, secondary teeth distinctly larger, apex long to short-acuminate, rarely acute;

surfaces abaxially glabrous to sparsely pubescent or infrequently villous, moderately resin-coated.

blade narrowly elliptic to rhombic, rarely ovate, 4–9 × 2–5 cm, base cuneate to rounded, margins flat, finely serrate or serrulate, sometimes slightly lobed, without noticeably larger secondary teeth, apex acute or obtuse to rounded;

surfaces abaxially sparsely pubescent to villous.
Inflorescences

formed season before flowering and exposed during winter; staminate catkins in 1 or more clusters of 3–6, 3.5–10 cm; pistillate catkins in 1 or more clusters of 2–7.

formed season before flowering and exposed during winter; staminate catkins in 1 or more clusters of 3–7, 3–10 cm, stamens 2, or 4 with 2 reduced in size; pistillate catkins in 1 or more clusters of 2–6.
Infructescences

ovoid, ellipsoid, or nearly cylindric, 1–2.5 × 0.8–1.5 cm;

peduncles 5–10 mm.

ovoid to nearly cylindric, 1–2.2 × 0.7–1 cm;

peduncles 1–10 mm.
Winter

buds stipitate, ovoid, 4–8 mm, apex rounded;

stalks 1.5–4 mm;

scales 2, equal, valvate, sometimes incompletely covering underlying leaves, moderately resin-coated.

buds stipitate, ellipsoid to obovoid, 3–9 mm, apex rounded;

stalks 3–5 mm;

scales 2, equal, valvate, sometimes incompletely covering underlying leaves, moderately to heavily resin-coated.
Flowering

before new growth in spring.

before new growth in spring.
Samaras

elliptic to obovate, wings narrower than body, irregular in shape, leathery.

broadly elliptic, wings narrower than body, irregular in shape, leathery.

Alnus oblongifolia

Alnus rhombifolia
Phenology Flowering early spring. Flowering early spring.
Habitat Sandy or rocky stream banks and moist slopes, often in mountain canyons Open, rocky stream banks and adjacent (often rather dry) slopes
Elevation 1000–2300 m (3300–7500 ft) 100–2400 m (300–7900 ft)
Distribution
from FNA
AZ; NM; Mexico (n Chihuahua and n Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; MT; OR; WA
[WildflowerSearch map]
[BONAP county map]
Discussion

Alnus oblongifolia is closely related to the Mexican and Central American A. acuminata, with which it has sometimes been confused. It is found only in scattered populations in the temperate deciduous forest vegetation zone of high mountains in the arid Southwest.

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

Alnus rhombifolia is the common alder throughout the dry Mediterranean climatic zone of coastal western United States. Mexican populations are not known, but because A. rhombifolia has been collected as far south as San Diego, California, it should be expected in adjacent Baja California.

Native Americans used various parts of Alnus rhombifolia medicinally for diarrhea, consumption, and burns, as a blood purifier, an emetic, and a wash for babies with skin diseases, and to facilitate childbirth (D. E. Moerman 1986).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 3. FNA vol. 3.
Parent taxa Betulaceae > subfam. Betuloideae > Alnus Betulaceae > subfam. Betuloideae > Alnus
Sibling taxa
A. glutinosa, A. incana, A. maritima, A. rhombifolia, A. rubra, A. serrulata, A. viridis
A. glutinosa, A. incana, A. maritima, A. oblongifolia, A. rubra, A. serrulata, A. viridis
Synonyms A. rhombifolia var. bernardina
Name authority Torrey: in W. H. Emory, Rep. U.S. Mex. Bound. 2: 204. (1859) Nuttall: N. Amer. Sylv. 1: 49. (1842)
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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