Greenleaf Manzanita is a species in the Ericaceae (Heath) family known by the scientific name arctostaphylos patula. A shrub which flourishes in the Sierras and Klamath mountains, it is also extant in the San Bernardino Mountains. It grows at higher elevations and is capable of surviving very cold winters. The distribution of arctostaphylos patula is one of the most widespread of the manzanitas, spanning most of western North America. Its northern edge is in Washington state, eastern edge in Colorado, western edge the North American coast, and southern most edge in Baja California. It spans in elevation from about 1,500 to 12,000 feet.
It reaches between three and seven feet in height.
Like other manzanitas, its lower branches extend more outward than upward and may root in the soil where they touch. The stems are twisting and reddish-brown in color, and shiny due to hairy secretion. The leaves are oval-shaped to nearly round, and flat, shiny, and smooth. They are roughly two-and-a-half inches long and an inch-and-three-fifths wide at maximum. The petioles may sometimes have clear-to-glandular hairs.
The plentiful flowers bloom in the winter and spring, are white to pink and urn-shaped, each with five small lobes at the mouth of the corolla, hanging in bunches. The fruits are dark brown drupes nearly a centimeter wide, each containing about five hard-coated seeds. Seeds are primarily dispersed by seed-caching mammals, and sometimes the fruits are consumed and dispersed by birds and medium-to-large mammals such as bears, coyotes, coatis, and foxes. It is also an important browse plant for deer
The Greenleaf Manzanita is not likely bound for extinction, as the seeds can remain dormant in soil for hundreds of years. The seeds do, however, like other types of manzanita, require a near encounter with fire followed by cold conditions to germinate. In some instances, greenleaf manzanitas produce lignotubers from which they can reproduce vegetatively.
Greenleaf manzanita is a drought-tolerant shrub, but does not fare well in alkaline soil.
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 inhibits the growth of Pacific ponderosa pine (pinus ponderosa var. ponderosa) and coast Douglas-fir (pseudotsuga menziesii var. menziesii) seedlings. Greenleaf manzanita’s ability to severely deplete available soil moisture is the greatest contributing factor in greenleaf manzanita inhibition of Pacific ponderosa pine seedling growth. The ability to extract water from moisture-depleted soil is likely attributable to a better-developed root system than that of conifer seedlings.
The greenleaf manzanita’s companion trees include white fir (abies concolor); red fir (abies magnifica); desert mountain mahogany (cercocarpus ledifolium); dogwood (cornus sp.); western juniper (juniperus occidentalis); tanoak (notholithocarpus densiflorus); ninebark (physocarpus capitatus); pinus sp.; quaking aspen (populus tremuloides); and canyon oak (quercus chrysolepis). Its companion shrubs include mountain grape (berberis aquifolium); ceanothus sp.; buckwheat (eriogonum sp.); coffeeberry (frangula sp.); honeysuckle (lonicera sp.); western Labrador tea (rhododendron columbianum); and huckleberry (vaccinum sp.).
The greenleaf manzanita is a confirmed host to 20 butterflies and moths, including the ceanothus silkmoth (hyalophora euryalus), the elegant sheepmoth (hemileuca eglanterina); the Mendocino silk moth (saturnia mendocino); the lappet moth (phyllodesma americana); the forest tent caterpillar (malacosoma disstria); small-eyed sphinx (paonias myops); the western tent caterpillar (malacosoma californica); the Vashti sphinx moth (sphinx vashti); epinotia arctostaphylana; hesperumia fumosaria; aethaloida packardaria; acronicta perdita; nemoria glaucomarginaria; pseudochelaria manzanitae; chionodes occidentella; aseptis ethnica; epinotia subplicana; gelechia panella; and coleophora glaucella. It is a likely host to 34 other butterflies and moths.
Some Plateau Indian tribes drank a tea of greenleaf manzanita as a cathartic.
From https://calscape.org; Plant Ecology by Christopher Moore and Stephen Vander Wall; Wikipedia; https://www.fs.fed.us; Western Forests (The Audubon Society Nature Guides) by Stephen Whitney; the US Forest Service’s website; Nch’i-Wana, “The Big River”: Mid-Columbia Indians and Their Land by Eugene Hunn.