FOREST TREES OF THE PACIFIC SLOPE. 423 



of one type, a principal leaf stein with few or many pairs of (leaf-like) leaflets 

 arranged on two opposite sides and a single leaflet at the end, so that the total 

 number is always odd. The twigs and branches, also', have a characteristic 

 arrangement in opposite pairs at every joint. Flowers appear in early spring, 

 usually before the leaves. They are usually small or minute and inconspicuous, 

 though densely clustered and are either perfectly bisexual or of separate sexes. 

 When of separate sexes the sexes are borne on separate trees. Occasionally 

 some bisexual flowers and some of one sex only are borne on the same tree. 



Fruits or " seeds," borne in branched clusters, have a general similarity in 

 form in all the ashes and are always produced in one season, ripening in early 

 autumn, but often remaining on the trees for several weeks afterward. The 

 "seed" has a thin wing at one end which adds greatly to its buoyancy and 

 enables the wind to waft it to considerable distances from the mother tree. 

 Seeds are also disseminated to some extent by streams and flood waters. At 

 least a small proportion of the crop Is eaten by mice and other small rodents. 

 Falling to the ground in autumn or winter they germinate, if at all, the follow- 

 ing spring, very rarely retaining their vitality for a longer time. 



Nearly 40 species are known, 16 of which occur in the United States, and all 

 are trees except one, a shrub. Three arborescent and one shrubby species 

 inhabit the Pacific region. One tree is confined to that region, while the other 

 two barely extend into it from their principal, more eastern range. The largest 

 and best timber ashes belong to the eastern United States. 



Leatherleaf Ash. 



Fraxinus coriacea Watson. 



DISTINGUISHING CHARACTERISTICS. 



Leatherleaf ash has no field name. The one suggested here is derived from 

 the character of its leaves, to which the technical name refers. 



It was distinguished about thirty years ago under its present name, but until 

 recently it has been confused with /•'. velutina, the range and habits of which are 

 much the same. Still imperfectly known, especially as regards range and silvical 

 characteristics. Similar in size and general appearance to F. velutina (but occa- 

 sionally of large diameter). It differs in having thicker, leathery, longer- 

 stemmed, broader leaflets, 5 in number, which are 2i to 3 inches long and 1} to 2 

 inches broad (fig. 201), deep green and smooth above, lighter beneath, with 

 minute soft hairs (sometimes smooth). Occasional leaves have 3 leaflets, or are 

 simple and single bladed. .Margins of the leaflets rather coarsely toothed, the 

 teeth far apart. Twigs of a season's growth are covered with fine, soft down. 

 The flowers are as in F. velutina, but they appear a few weeks earlier, and usu- 

 ally before the leaves come out, but sometimes with them. Clusters of mature 

 fruit (fig. 201) are narrow, 2* to 3 inches long, and the seeds few. Wood, not 

 yet studied. The tree is of too rare occurrence in the Pacific region to be of 

 economic importance there. 



Longevity. — Not fully determined. Record of one tree 1\\ inches in diameter 

 shows an age of 48 years. 



Desert regions of southern Utah, northern Arizona, southern Nevada, and south- 

 eastern California. 



