Arctostaphylos patula

Greenleaf manzanita

Ericaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (flowering plants). Class - Magnoliopsida. Subclass - Dilleniidae. Order - Ericales. Family - Ericaceae (heath). Genus - Arctostaphylos Adans. Species - Arctostaphylos patula Greene

Ecology: Greenleaf manzanita is a drought-tolerant shrub. Greenleaf manzanita is shade intolerant, prefers disturbed sites, and typically is an early to midseral species. Its ability to colonize quickly after disturbance and interfere with conifer seedling growth allows it to dominate for many decades after disturbance. Without further disturbance, conifers eventually overtop greenleaf manzanita. Greenleaf manzanita may still inhibit conifer growth after being overtopped until canopy closure shades it out. In the absence of further disturbance, it may take from 30 to 100 years for conifers to gain dominance over shrubs Greenleaf manzanita had many uses for Native Americans. The fruits were eaten whole, made into cider and jelly, and brewed into tea to treat poison-oak (Toxicodendron diversilobum) exposure.

Identification

Shrubs, erect or mound-forming, 1-3 m; burl usually absent, sometimes flat, obscure; twigs usually densely short-hairy with golden glands on tips of hairs, rarely short white-hairy and eglandular. Leaves: petiole 7-15 mm; blade bright green (lightly gray-green if short-hairy), shiny, widely ovate to orbiculate, 2.5-6 × 1.5-4 cm, base rounded, truncate, or slightly lobed, (not clasping), margins entire, plane, surfaces smooth, glabrous or, rarely, short-hairy. Inflorescences panicles, 2-8-branched; immature inflorescence pendent, branches spreading, axis 1.5-3 cm, 1+ mm diam., hairy with golden glands on tips of hairs or short-hairy and eglandular; bracts appressed with incurved tips, scalelike, deltate, 4-6 mm, apex acuminate, surfaces usually densely tomentose with golden glands on tips of hairs, rarely short white-hairy and eglandular. Pedicels 2-7 mm, glabrous or white-hairy. Flowers: corolla mostly pink, conic to urceolate; ovary glabrous or white-hairy. Fruits depressed-globose, sometimes subglobose, 7-10 mm diam., glabrous. Stones distinct. 2n = 26. Unlike greenleaf manzanita populations elsewhere, greenleaf manzanita in the Sierra Nevada and southwestern Oregon has a lignotuber. The lignotuber is described as a heavy, turnip- or globular-shaped organ that may form tabular platforms.

Threats

Fire effects: Greenleaf manzanita is generally top-killed by fire where it forms a lignotuber. In the absence of a lignotuber, fire may kill greenleaf manzanita. Greenleaf manzanita with lignotubers sprout after fire unless the entire periphery of the lignotuber is deeply charred, which rarely happens. Shrubs produce new sprouts from dormant buds on the lignotuber in as little as 10 days to 3 weeks. Greenleaf manzanita plants with a lignotuber can withstand repeated burnings. The dormancy of greenleaf manzanita seeds stored in soil and duff is broken by fire scarification...Higher-severity fires caused greater seedling establishment than lower-severity fires.

Reproduction

Seed Production - Greenleaf manzanita is insect pollinated. Greenleaf manzanita produces large seed crops nearly every year. In a mixed-conifer community of the Sierra Nevada, greenleaf manzanita populations produced a mean of 10,000 seeds/acre. In general, greenleaf manzanita plants do not begin to flower and fruit until the age of 8 to 10. Where greenleaf manzanita populations sprout from a lignotuber, seed production is less than in nonsprouting populations. Greenleaf manzanita seeds are dispersed by birds and mammals including rodents, American black bears, and coyotes. Greenleaf manzanita utilizes a seed bank. The hard seeds of greenleaf manzanita can remain dormant in the soil for hundreds of years until stimulated to germinate. Greenleaf manzanita seeds require scarification (by heat or disturbance such as logging activities) followed by a period of cold stratification for germination to occur. Seeds generally germinate on burned sites in the spring.

Vegetative Regeneration - Greenleaf manzanita regenerates vegetatively by layering and sprouting from the lignotuber.

Species Distribution

Citation

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

The Jepson Herbarium
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97. Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.