Cornus nuttallii

Pacific dogwood

Cornaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (flowering plants). Class - Magnoliopsida (dicotyledons). Subclass - Rosidae. Order - Cornales. Family - Cornaceae (dogwood). Genus -Cornus L. Species - Cornus nuttallii Audubon

Ecology: Although typically considered a mesic species, Pacific dogwood is quite drought tolerant. Pacific dogwood's low frost tolerance, high flood tolerance, and moderate shade tolerance make it common along stream banks and in low-elevation coniferous, hardwood, and mixed coastal forests with temperate to mesothermal climates. Pacific dogwood can tolerate early-, mid-, and late-seral conditions...As a subcanopy species, Pacific dogwood has several shade growing adaptations. At 1/3 full sunlight, Pacific dogwood maintains maximum photosynthetic potential. Branches are self-shading; leaf petioles orient downward allowing leaves to rest on and shade the branches. Although the trunk of Pacific dogwood can be damaged by direct sunlight, established plants may initiate shoot growth from the crown to shade and protect the exposed trunk.

Identification

The growth form of Pacific dogwood may change with site conditions. When grown under a canopy of vegetation, the trunk is normally tapered and the crown is slender and short. Habit: Shrub, tree, < 25 m. Stem: twigs green, hairy; bark in age dark red to +- black. Leaf: blade 6--12 cm, narrow-elliptic to obovate, adaxially appressed-puberulent, abaxially paler, hairier; petiole 5--10 mm. Inflorescence: head-like; bracts 4--7, 4--6 cm, 3--6 cm wide, showy, +- white, persistent; receptacle convex. Flower: sepals 2.5 mm; petals 4 mm, +- green to white; style 2 mm. Fruit: 1--1.5 cm, elliptic, generally angled from crowding, red; stone smooth.

Threats

In the WFDP: Pacific dogwood is susceptible to suppression-induced mortality in this energy-limited system. The primary pathogen affecting Pacific dogwood in the WFDP is Armillaria root rot (aka Honey fungus; Armillaria spp.).

Fire effects: The immediate effect of fire on Pacific dogwood varies with fire severity. Low-consumption, early-spring fires, in mature mixed conifer ecosystems of the northern Sierra Nevada, produced temperatures hot enough to kill Pacific dogwood foliage but not hot enough to kill buds protected by bark. After being burned, Pacific dogwood typically sprouts from the root crown.

Pests and pathogens: Botanical characteristics are altered when plants are infected with dogwood anthracnose, a nonnative fungal disease caused by Discula spp., common in Pacific dogwood. Fungal activity is usually greatest from May through early July. However, the fungus can be active any time conditions are moist and plants are growing. Infected leaves develop blotches and often drop early. Defoliation can be extreme. Twigs with this fungal disease are depressed in spots and allow the fungus to progress into leaf buds, killing them and setting back spring emergence. Seed production diminishes with anthracnose infection. This fungal disease is considered threatening to native Pacific dogwood populations because of its rapid spread and severe effects.

Reproduction

Flowering and fruiting - Pacific dogwood flowers are chiefly pollinated by insects. Pacific dogwood commonly flowers twice in a growing season. This phenomenon may be related to late-summer water stress. Flowers appear 1st in the spring (April, May, or June). In late summer or early fall, flowering often occurs again. Fruits are often ripe by September or October.

Seed dispersal and growth - The fleshy fruit surrounding Pacific dogwood seeds is likely attractive to bird and small mammal seed dispersers. While shading seems important to seedling emergence, deep shade may not provide for establishment, growth, and reproduction of Pacific dogwood.

Vegetative regeneration - Pacific dogwood readily sprouts from the root crown following disturbance and top-kill.

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.

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. $131.95, hardcover; 1600 pages. ISBN-13: 978-0520253124.

Burke Museum of Natural History and Culture
Burke Museum. 2016 [Online]. University of Washington.