184 ALNUS 



or oval, 3 to 6 ins. long, 2 to 4 ins. wide, rounded or broadly wedge-shaped at 

 the base, pointed, the margins decurved and with numerous small lobes or 

 large teeth, each again unequally toothed ; nerves parallel, reddish, ten to 

 fifteen pairs ; upper surface dark green, lower one pale or greyish, covered at 

 first with down which mostly falls away except on the nerves ; stalk ^ to I in. 

 long. Male catkins 4 to 6 ins. long, J in. wide, usually three to five in a cluster. 

 Fruits I to | in. long, barrel-shaped^ three to six together. 



Native of Western N. America from Alaska, to California ; introduced 

 sometime previous to 1880, since when it has been grown at Kew. It is a hand- 

 some and striking alder, both when in flower in March and when in full foliage 

 later. Jepson observes that in some parts of California it forms " pure groves 

 of great beauty in bottom lands near the sea." 



A. RHOMBIFOLIA, Nuttall. WHITE ALDER. 



A tree 30 to 100 ft. high; forming a thin, spreading, round-topped head of 

 branches, pendulous at the ends : young branches at first covered with pale 

 hairs which soon fall away. Leaves ovate, oval, or rounded, ordinarily 2 to 4 

 ins. long, about two-thirds as wide ; usually pointed (sometimes rounded) at the 

 apex, tapered at the base, unevenly or doubly toothed ; dark shining green (but 

 at first very hairy) above ; paler, yellowish, and permanently downy beneath. 

 Male catkins two to seven in a cluster, opening on the naked shoots early in 

 spring, each catkin 3 to 5 ins. long ; stamens two, rarely three. Fruits \ to | 

 in. long, three to seven together. 



Native of Western N. America. The leaves occasionally approach the 

 diamond shape indicated by the name, and' on vigorous shoots are up to 5 ins. 

 long. According to Jepson, this alder keeps to streams which do not run dry, 

 forming files of trees in mountain gorges which are "to the traveller a reliable 

 sign of water." It is very rare in cultivation, the plant supplied for it in this 

 country and on the Continent being, as a rule, A. oregona. 



A. SERRULATA, Willdenow. SMOOTH ALDER. 

 (A. rugosa, C. Koch?) 



A shrub, sometimes a small tree 30 to 40 ft. high ; young twigs slightly 

 downy and viscid. Leaves obovate (sometimes oval), rounded or pointed at 

 the apex, always tapered at the base ; minutely, often unevenly toothed ; i^ to 

 4 ins. long, one-half as much or more wide, smooth above, downy to nearly 

 smooth beneath ; stalk to f in. long. Male catkins up to 4 ins. long, appear- 

 ing in spring before the leaves. Fruit oval, f in. long. 



Native of the eastern United States, from Maine to Florida ; introduced in 

 1769. From A. lincana this is distinguished by the more tapered (never 

 rounded) base to the leaf, which is green on both sides, and usually broadest 

 above the middle ; and from its fellow American shrubby species, A. viridis, 

 by flowering on the naked wood before the leaf-buds move, and by the very 

 finely toothed leaves. A very hardy shrub, but of no particular merit for 

 gardens. 



A. SITCHENSIS, Sargent. SITKA ALDER. 



This tree is a native of Western N. America, from the borders of the Arctic 

 Ocean to Oregon. It was introduced in 1903 to Kew by Professor Sargent, 

 who describes it as a tree sometimes 40 ft. high, with a trunk 2 ft. in girth, 

 forming a narrow head of short and nearly horizontal branches ; but some- 

 times a mere shrub, and forming thickets ; young shoots finely downy at first, 

 and very glandular. Leaves ovate, 3 to 6 ins. long, i-| to 4 ins. wide, rounded 

 or broadly wedge-shaped at the base, pointed, doubly toothed ; light green 



