Ontario Weeds: Prickly ash
Excerpt from Publication 505, Ontario Weeds,
Order this publication
Table of Contents
- Other Names
- General Description
- Stems and Roots
- Flowers and Fruit
- Similar Species
- Related Links
Name: Prickly-ash, Xanthoxylum americanum
Other Names: clavalier d'Amérique, frêne épineux, Zanthoxylum americanum Mill.
Family: Rue Family (Rutaceae)
General Description: Tail shrubs or small trees up to 8m (26ft) high; reproducing by seed and sprouting from spreading underground rhizomes, often forming dense impenetrable stands.
Prickly-ash. A Branch with 5 compund leaves and young fruits. B. Flowering branch in spring before leaves emerge.
Stems & Roots: Stems very prickly
with pairs of stout, triangular prickles at every node, the needle-sharp
tip of each prickle pointing outwards or slightly upwards.
Leaves: Leaves pinnately compound with 2 to 5 pairs of leaflets and 1 terminal leaflet; leaflets narrowly to broadly ovate with a pointed tip, dark green above and light green below, very finely hairy on the underside when young but later becoming smooth, with very small translucent dots due to the presence of oil glands, these resembling pinpricks through the leaf when viewed against the light; leaf margins very shallowly toothed to almost smooth and with a tiny yellowish gland in the base of the notch between the teeth.
Flowers & Fruit: Flowers unisexual, in small umbel-like clusters from the nodes of branches of the previous year and appearing in May before the leaves expand; males and females on different plants; petals 4 or 5, yellowish, very small, 1-2mm (1/25-1/12in.) long; sepals absent; stamens 4 or 5 and longer than the petals in male (pollen-producing) flowers; pistils 3 to 5 in female (seed-producing) flowers, forming small, stalked, spherical or elliptical pods about 5mm (1/5in.) across and splitting across the top to release 2 seeds. Flowers in May; seeds mature in August to September.
Habitat: Prickly-ash occurs in woods and moist meadows in southern and southwestern Ontario.
Similar Species: It is distinguished
from wild and cultivated roses, Rosa spp., [rosier] by its
clusters of small yellow flowers on leafless branches in May, and
by its pairs of triangular prickles at each node of the stem, rather
than irregularly scattered along the stem. Taller shrub and tree
forms of Prickly-ash might be confused with Black locust, Robinia
spp. [robinier] or Honey-locust, Gleditsia spp. [février]
which have compound leaves and may also have pairs of prickles on
the stems at the base of each leaf, but it can be distinguished
by its small yellow, unisexual flowers that blossom on leafless
branches in May, whereas the two locusts have larger, showy, pea-like
flowers that blossom after the leaves are out, and by the leaflets
of its once-compound leaves having translucent dots and very shallow
teeth with tiny yellow glands between the teeth. Its smooth-margined,
pinnately compound, alternate leaves resemble those of Poison
sumac but its pairs of spines and early yellow flowers are distinctive.
Caution: Because the foliage may be browsed when other forage is scarce and because it has been suspected of having poisoned cattle and sheep in Indiana, it should be viewed with suspicion when present in areas used for pasturing livestock.
For more information:
Toll Free: 1-877-424-1300