Flora of North America species comparison

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Arbutus menziesii

Arbutus

arbutus, madrone, madrono, Pacific arbutus, Pacific madrona, Pacific madrone

madrone, madroña, madroño
Habit Shrubs or trees, 4–10(–20) m; bark dark red, smooth, until mid season when outer bark exfoliates, inner bark green, soon weathering to dark red; following exfoliation on younger wood, bark retained on oldest portions of main axis and on abaxial sides of larger lateral axes, area of retained bark gradually increasing as tree ages, becoming roughened dark gray. Shrubs or trees, sometimes with swollen burl-like base (capable of resprouting after fire); bark red or reddish brown, exfoliating in flakes on young axes, retained on oldest portions of trunk and abaxial side of major limbs where forming an irregular checked pattern, or bark at first flaking on young branchlets then retained, eventually uniformly checkered over all main axes (A. arizonica).
Stems

erect, branching;

young branchlets glandular-hairy, thinly tomentose, or both, or glabrous;

new growth of rapidly elongating sprouts usually with glandular hairs; (buds ovate, apex acute, glossy red, sometimes glabrate, usually only terminal buds well developed and conspicuous; bud scales accrescent, 8–16, imbricate).
Leaves

larger on sterile shoots with longer internodes;

petiole 2–4.5 cm, base slightly decurrent, glabrous, sometimes with hairs adaxially;

blade glaucous-green abaxially, olive-green adaxially (leaves of previous season turning yellow and red in June and July before they fall), elliptic, 6.5–13 × 3.5–6(–8) cm, base usually rounded, sometimes slightly cordate, rarely tapered, apex usually rounded or acute, rarely with short cusp, surfaces glabrescent (sparingly hairy on newly emerging leaves).

bifacial or isofacial;

blade ovate (widest slightly proximal to middle) or elliptic, coriaceous, margins entire or finely to coarsely toothed on sprouts and sterile shoots, plane, surfaces ± glabrous.
Inflorescences

(often compound), congested or not;

axes hairy ± throughout, hairs not glandular.

clusters of racemes, 10–40-flowered.
Pedicels

accrescent, initially pendulous, becoming stiffly erect, 3–5(–6.2) mm, (to 6–8 mm in fruit), sometimes sparsely glandular-hairy;

bract clasping base, rust-colored, scalelike, 2–3.5 mm.

Flowers

calyx creamy tan at anthesis, lobes 1–2.1 mm, apex blunt;

corolla 4.9–5.8 mm;

anthers 1–1.2 mm, spurs usually slightly exceeding length of thecae;

ovary with 2–5 ovules per locule.

bisexual;

sepals persistent, 5, connate basally, ovate to deltate;

petals 5, connate nearly their entire lengths, creamy white [yellowish], corolla urceolate, (soon developing post-anthesis circumferential dimple near mid length, base inflated);

stamens 10, included, (distinct);

filaments slender distally, abruptly expanded proximally into swollen base, (villous proximally);

anthers with 2 dorsal awns adaxially, dehiscent by subterminal, elliptic pores;

ovary 5-locular;

stigma capitate.
Berries

red or orange-red, 13–20 mm diam.

orange-red, red, or blackish red, ± globose or slightly turbinate, juicy, roughened-tuberculate, glabrous or thinly hairy;

pyrenes 1–5, not connate into stone.
Seeds

2–2.5 mm.

1–5, distinct, (irregularly angled).
x

= 13.

Arbutus menziesii

Arbutus
Phenology Flowering Mar–May(-Jun); fruiting (Jun-)Jul–Sep (-Oct) (fruit sometimes held on the trees into early part of following year).
Habitat Open forests, rocky slopes, ravines, foothills, and shores
Elevation 0-1800 m (0-5900 ft)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from USDA
w North America; Mexico; Central America; sw North America; s Europe; w Europe; n Africa; n Atlantic Islands (Canary Islands)
[BONAP county map]
Discussion

References to the presence of Arbutus menziesii in the San Pedro Martír Mountains of northern Baja California have not been supported by vouchers. Its southernmost area of occurrence is in San Diego County, California, where it is rare. Its range extends northward along the coast to British Columbia (about 50° north latitude, in the vicinity of Seymour Narrows).

The smooth, red bark and its mid-season exfoliation mark Arbutus menziesii as a distinct species and one much sought as an attractive landscape tree. People who have acquired property with native individuals of the species already present are very lucky because transplants of young saplings for landscaping seldom succeed. Cultivation from seed seems to be successful.

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

Unedo Hoffmansegg & Link

Species 10 (3 in the flora).

Five species of Arbutus occur in the Neotropics, and all extend north of the Tropic of Cancer. In the Tropics, the plants are found primarily in montane areas associating with Pinus and Quercus species. Populations north of Mexico inhabit riverine woodlands (A. arizonica) or progressively drier environments, associating with pinyon-juniper vegetation (A. xalapensis) in Texas and New Mexico, and dry wooded slopes and canyons (A. menziesii) in California, Oregon, and southwestern Washington, increasingly moist but well-drained habitats in northwestern Washington, islands of Puget Sound and San Juan Archipelago, and southwestern British Columbia.

Species of Arbutus are easily confused with some members of the genus Comarostaphylis because of the exfoliating bark and berrylike fruit common to both. The fruit alone distinguishes them: Arbutus species produce a true berry with multiple locules and seeds, whereas Comarostaphylis species produce a drupe with one central stone enclosing a single seed. Taxonomically, the Arbutus species of the Old World and New World are included in a single genus. A. P. de Candolle (1839) perceived a morphological distinction between the two geographic groups. He maintained a single genus and established two subgenera that he named Gerontogeae (sect. Arbutus) for the Old World taxa and Americanae for those of the New World. L. C. Hileman et al. (2001) presented corroborative molecular data suggesting that the two geographic groups represent separate lineages.

Arbutus unedo is cultivated as an ornamental tree in California, where it flowers and fruits. It is reported to succeed in the USDA hardiness zones 8–10, extending along the Pacific Coast from southwestern Oregon into the region north of Los Angeles, California. It grows also in all of coastal Washington and southwestern British Columbia.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blades usually tapered-acute at base, rarely rounded; bark light gray to reddish gray, checkered with squarish to rectangular segments or plates, 1-4 × 1-2.5 cm, retained on bole and major limbs; twigs 3+ years old with brick-red outer bark exfoliating in flakes or, sometimes, in slender strips.
A. arizonica
1. Leaf blades usually rounded or subcordate at base, sometimes tapered; bark on young twigs exfoliating in irregular strips, exfoliating on larger limbs and bole in flakes and sheets, older bark retained only at base of tree or on abaxial sides of larger limbs
→ 2
2. Plants 4-10(-20) m; leaf blades 6.5-13 × 3.5-6(-8) cm, glaucous-green abaxially; western coast of North America.
A. menziesii
2. Plants 2-4(-8) m; leaf blades (2.5-)4-6(-7.5) × (1.2-)1.8-3(-4) cm, green or slightly lighter green abaxially; New Mexico, Texas
A. xalapensis
Source FNA vol. 8, p. 399. FNA vol. 8, p. 398. Author: Paul D. Sørensen.
Parent taxa Ericaceae > subfam. Arbutoideae > Arbutus Ericaceae > subfam. Arbutoideae
Sibling taxa
A. arizonica, A. xalapensis
Subordinate taxa
A. arizonica, A. menziesii, A. xalapensis
Synonyms A. procera
Name authority Pursh: Fl. Amer. Sept. 1: 282. 1813 , Linnaeus: Sp. Pl. 1: 395. (1753): Gen. Pl. ed. 5, 187. 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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