Arctous
Ericaceae subfam. arbutoideae
alpine bearberry
prostrate, extensively branched, glabrous.
erect or prostrate.
deciduous (leaf or leaf bases marcescent), bifacial;
blade ovate or obovate to oblanceolate, subcoriaceous, margins crenate-serrate, ± plane, surfaces glabrous (margins ciliate toward base).
persistent (deciduous in Arctous), usually alternate, sometimes opposite or whorled (Ornithostaphylos), rarely opposite (Xylococcus);
petiole usually present, sometimes absent (Arctostaphylos);
blade plane, abaxial groove absent.
racemes (formed on current year’s growth), 2–7-flowered;
bracteoles absent.
terminal, panicles or racemes;
perulae absent;
bracts much shorter than sepals;
bracteoles 2 or absent (Arctostaphylos, Arctous).
bisexual;
sepals persistent, 5, distinct, broadly ovate;
petals 5, connate nearly their entire lengths, white, cream, yellow, or green, corolla urceolate;
stamens 10, included;
filaments dilated, (usually hairy at base);
anthers (reddish), with 2 (recurved), dorsal awns, dehiscent by 2 terminal pores;
ovary 4–10-locular;
stigma capitate.
pendulous;
sepals (4-)5;
petals (4-)5, connate, corolla deciduous, usually urceolate, sometimes cylindric, conic, or globose, lobes much shorter than tube;
intrastaminal nectary disc present;
stamens (8-)10;
anthers dehiscent by slits or pores;
ovary 2-10-locular;
placentation axile;
style straight.
drupaceous (baccate in Arbutus), (pulp mealy or juicy), indehiscent;
pyrenes 1-5, often connate into stonelike endocarp.
black-purple, brick red, or scarlet, globose, juicy, smooth;
pyrenes 4–5, distinct.
4–5, distinct, (ovoid), not angled; (testa bony).
1-10, usually distinct, sometimes connate, globose (sometimes 3-sided), not winged.
= 13.
Arctous
Ericaceae subfam. arbutoideae
Arctostaphylos Adanson subg. Arctous A. Gray in A. Gray et al., Syn. Fl. N. Amer. 2: 27. 1878
Species 3 or 4 (2 in the flora).
The genus Arctous differs vegetatively from Arctostaphylos in having leaves with winged petioles and crenate to serrulate margins, fruits that are bright red or black and juicy (in Arctostaphylos the fruits are mealy or granular), and only five nutlets with hard, smooth endocarps (in contrast to Arctostaphylos, where the fruits have ten sculptured nutlets). Arctous has flowering buds that develop in the spring, as opposed to Arctostaphylos, in which buds form in the summer and autumn and lie dormant during the winter. Phylogenetic studies employing molecular methods place Arctous as the sister group to Arctostaphylos. Both species of Arctous in the flora area turn bright orange-red in autumn and are suitable for the alpine or rock garden.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 6, species 91 or 92 (6 genera, 70 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades 4-15 mm, surfaces rugose, hairy toward base and on petiole (hairs 1-2 mm); twigs clothed with persistent old leaves or petioles; corolla lobes 0.5 mm; fruits black- purple; stones 2.7-4.6 × 2-3.6 mm. | A. alpina |
1. Leaf blades (10-)15-30(-60) mm, surfaces not or only slightly rugose, glabrous; twigs bare of old leaves; corolla lobes 1 mm; fruits brick red or scarlet; stones 2.5-3 × 1.6-2.2 mm. | A. rubra |
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