Fraxinus L. Ashes

common name: Olive

Description: The Genus Fraxinus contains deciduous trees (rarely shrubs) that have odd-pinnately compound opposite leaves. The leaves are without stipules, but have a petiole. The leaflets can be serrate or entire and sessile or petiolulate.(Preston, R., 1976). In the book North American Trees by Richard Preston, the flowers are described as "regular; perfect; dioecious or polygamous; small, but quite conspicuous in slender-branched panicles; appearing before or with the leaves; calyx 4-lobed or wanting; corolla usually 4-lobed or wanting; stamens usually 2 (rarely 3 or 4); single 2-celled ovary (rarely 3-celled); ovules suspended in pairs from inner angle of the cell." The ashes have 1-seeded chestnut-brown samara fruits. The oblong seed is packed into its cavity where it is safely carried by the wind. The twig shape ranges from thin to stout and they can be hairy or smooth. The leaf scar appearance varies from nearly round to semicircular. Usually the bundle scars are numerous. In winter, the terminal bud is larger than the lateral, but they both have 1-3 pairs of scales. The inner scales increase size with age. The bark has longitudinal channels and is thick. (Preston, R., 1976) The bark on some species has a spongy feel.

Species: The following list is from the book A Synonymized Checklist of the Vascular Flora of the United States, Canada, and Greenland written by John T. Kartesz. It lists 18 species of Fraxinus in the United States. The common names for the species were not given. The common names listed were taken from Richard Preston's North American Trees.

• americana L. White Ash
• anomala Torr. ex S. Wats. Singleleaf Ash
• berlandieriana DC. Berlandier Ash
• caroliniana P. Mill. Carolina Ash
• cuspidata Torr. Fragrant Ash
• dipetala Hook & Arn. Two-petal Ash
• excelsior L.
• gooddingii Little
• greggii Grey Gregg Ash
• latifolia Benth. Oregon Ash
• nigra Marsh. Black Ash
• papillosa Lingelsh.
• pennsylvanica Marsh. Green Ash
• profunda Bush Pumpkin Ash
• quadrangulata Michx. Blue Ash
• texensis Sarg. Texas Ash
• uhdei (Wenzig) Lingelsh.
• velutina Torr. Velvet Ash

(Kartesz, J.T., 1994)

Identification Guide: The following is a key to the species of ashes. This key was taken from a book that did not have all of the same species as listed above, however, most are accounted for.

"1. Flowers with corolla, perfect, showy, in terminal panicles; leaves 5-7 inches long, 3-7 lanceolate, stalked leaflets; southwestern....F. cuspidata, Fragrant Ash
1. Flowers without corolla, dioecious or polygamous, axillary panicles.

2. Leaflets 1/2-3/4 inch long, spatulate; leaves 1 1/2-3 inches long; southwestern....F. greggii, Gregg Ash
2. Leaflets 1-6 inches long; leaves (unless simple) over 3 inches long.

3. Twigs 4-angled; fruit compressed, oblong wing extending to base.

4. Leaves 8-12 inches long, 5-11 leaflets; flower with minute calyx; eastern....F. quadrangulata Blue Ash
4. Leaves 1 1/2-6 inches long, 1-5 leaflets; southwestern.

5. Leaflets 1 (rarely 2-3); fruit 1/2 inch long....F. anomala Singleleaf Ash
5. Leaflets 5 (rarely3); fruit 1-1 1/2 inches long.

6. California....F. dipetala Two-petal Ash
6. Arizona....F. lowellii Lowell Ash

3. Twigs terete.

7. Body of fruit compressed, wing extending to seed base.

8. Leaflets 7-11, sessile; wing oblong, flat; northern....F. nigra Black Ash
8. Leaflets 3-7, stalked; fruit elliptic, often 3-winged; southeastern....F. caroliniana Carolina Ash

7. Body of fruit nearly terete, wing not extending to base.

9. Wing terminal or not decurrent to below middle of seed cavity; leaflets stalked.

10. Leaflets crenulate-serrate to entire, glabrous; twigs nearly glabrous, leaf scars notched at top.

11. Leaves 8-12 inches long, 7 (rarely 5-9) leaflets; eastern....F. americana White Ash
11. Leaves 5-8 inches long, 5 (rarely 7) leaflets; Texas and Oklahoma....F. texensis Texas Ash

10. Leaflets sharply serrate, at least above middle, glabrous to hairy below; twigs glabrous to hairy, leaf scar truncate or slightly notched....F. pennsylvanica Green Ash

9. Wing decurrent to below middle of seed cavity.

12. Fruit 2-3 inches long, frequently 3-winged; leaflets soft-pubescent below; coastal and river swamps of eastern United States....F. profunda Pumpkin Ash
12. Fruit not over 2 inches long; western.

13. Lateral leaflets usually sessile; West Coast....F. latifolia Oregon Ash
13. Lateral leaflets stalked; southwestern.

14. Fruit 1-1 1/2 inches long; leaflets glabrous....F. berlandieriana Berlandier Ash
14. Fruit 3/4 inch long; leaflets tomentose below....F. velutina Velvet Ash"

General Information: There are 65 species throughout the Northern Hemisphere. This includes the tropical forests of Java. North America has 18 species. The ashes grow quickly. They have a fibrous root system and are relatively untroubled by damaging insects or fungi.(Preston, R., 1976) Ash trees are highly valued as timber. White Ash wood is preferred over Green Ash wood because it is less brittle and more resilient, but the two are often mixed and used for the same function. They are also seen in landscaping and reclamation projects because of their rapid growth. (Brown et al.,1990). Many times the White Ash and the Green Ash are confused for each other. One source of this confusion is the leaflet size. The Green Ash tends to have smaller mature leaflets than the White Ash, but young White Ash leaflets are also small. As the White Ash matures, its leaflets get bigger. (Preston, R., 1976) Depending on one's familiarity with the two species, distinguishing the two can be a troublesome task. The difference can be told by the leaf scars. The Green Ash leaf scars are half-round whereas the White Ash has deeply notched leaf scars.(Brown et al.,1990).The shape of the fruit for both the Green Ash and the White Ash is an aid to tell them apart from other species of the Genus Fraxinus. The wing begins on the lower part of the actual seed capsule for Green and White Ashes. There are other species whose wing begins closer to the top of the seed capsule.

This picture demonstrates the ideal difference between the two species leaflets.

References:

1. Brown, C. & Kirkman, K. 1990. Trees of Georgia and Adjacent States. Timber Press, Inc. Portland, Oregon.
   


2. Collingwood, G.H. & Brush, W.. 1974. Knowing your trees. The American Forestry Association. Washington D.C..
   


3. Kartesz, J.T. 1994. A Synonymized Checklist of the Vascular Flora of the United States, Canada, and Greenland. v1. 2nd edition. Timber Press, Inc. Portland, Oregon.
   


4. Preston, R. 1976. North American Trees. The Iowa State University Press. U.S.A.
   


5. Watts, M. 1991. Tree Finder: A Manual for the Identification of Trees by Their Leaves. Nature Study Guild. Rochester, NY.