|Alnus subsp. var.||Alder|
|Standard Cyclopedia of Horticulture|
Alnus (the ancient Latin name). Betulaceae. Alder. Ornamental woody plants grown chiefly for their foliage; some species are valuable as timber trees.
Trees or shrubs: lvs. alternate, deciduous, short-petioled, usually serrate or dentate: fls. monoecious, apetalous, in catkins; staminate ones elongated, each bract with 3 fls.; stamens 4 in each fl., with short filaments not divided at the apex; pistillate catkins short, each bract with 2 fls.; styles 2; the pistillate catkins developing into a ligneous, generally ovoid cone with persistent, 5-lobed scales: fr. a small nutlet.—About 30 species in the northern hemisphere, in Amer. south to Peru. Monograph by Winkler in Engler's Pflanzenreich: Betulaceae 101 (1904).
The alders are deciduous trees, or shrubs with medium-sized leaves and pendulous staminate catkins in spring before the leaves; the short pistillate catkins developing into woody cones about 1/2 to 1 inch long and usually arranged in small racemes. The profuse male catkins are pleasing in early spring. The wood is valuable for its durability in water; of the native species, A. rubra is the most important timber-tree; in the Old World, A. glutinosa and A. japonica. Most species are suitable for planting on damp soil, where they grow rapidly, but A. cordata prefers a drier situation; also A. japonica, A. incana and A. tinctoria grow well in drier situations.
Usually propagation is by seeds gathered in the fall and well dried; sown in spring with but slight covering, and kept moist and shady, they germinate soon; a slight covering with moss, taken on when the seedlings appear, will be useful. At the end of the same year or the following spring, the seedlings are transplanted, usually into rows 1 to 2 feet apart and 6 inches from each other. After two years, they may be planted where they are to stand. The shrubby species, also A. glutinosa, grow from hardwood cuttings placed in moist and sandy soil, also from layers, and A. incana from suckers. Rarer kinds are grafted on common potted stock in early spring in the propagating-house; grafting out-of-doors is rarely successful. CH
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Pests and diseases
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Classification according to Wikipediawp: The genus is divided into three subgenera:
Subgenus Alnus. Trees. Shoot buds stalked. Male and female catkins produced in autumn (fall) but staying closed over winter, pollinating in late winter or early spring. About 15-25 species, including:
- Alnus acuminata - Andean Alder. Andes Mountains, South America.
- Alnus cordata - Italian Alder. Italy.
- Alnus cremastogyne
- Alnus glutinosa - Black Alder. Europe.
- Alnus incana - Grey Alder. Europe & Asia.
- Alnus japonica - Japanese Alder. Japan.
- Alnus jorullensis - Mexican Alder. Mexico, Guatemala.
- Alnus nepalensis - Nepalese Alder. Eastern Himalaya, southwest China.
- Alnus orientalis - Oriental Alder. Southern Turkey, northwest Syria, Cyprus.
- Alnus rhombifolia - White Alder. Interior western North America.
- Alnus rubra - Red Alder. West coastal North America.
- Alnus serrulata - Hazel alder, Tag Alder or Smooth alder. Eastern North America.
- Alnus subcordata - Caucasian Alder. Caucasus, Iran.
Subgenus Clethropsis. Trees or shrubs. Shoot buds stalked. Male and female catkins produced in autumn (fall) and expanding and pollinating then. Three species:
- Alnus formosana -Formosan Alder Taiwan
- Alnus maritima - Seaside Alder. East coastal North America, plus disjunct population in Oklahoma.
- Alnus nitida - Himalayan Alder. Western Himalaya.
Subgenus Alnobetula. Shrubs. Shoot buds not stalked. Male and female catkins produced in late spring (after leaves appear) and expanding and pollinating then. One to four species:
- Alnus viridis - Green Alder. Widespread:
- Alnus viridis subsp. viridis. Eurasia.
- Alnus viridis subsp. maximowiczii (A. maximowiczii). Japan.
- Alnus viridis subsp. crispa (A. crispa). Northern North America.
- Alnus viridis subsp. sinuata (A. sinuata, Sitka Alder or Slide Alder). Western North America, far northeastern Siberia.
- A . acuminata, HBK. Tree: lvs. usually ovate and pubescent beneath, doubly serrate. Cent. Amer., north to Ariz. CH
- A. cremastogyne, Burkill. Tree: young branchlets glabrous; lvs. oblong-obovate, glabrous, sharply serrate, 3-4 in. long: cones cylindric, solitary on slender peduncles, about 1 1/2 in. long. W.China. — Recently intro., probably not hardy N. CH
- A. firma, Sieb. & Zucc. (A. Sieboldiana, Mats.). Allied to A. yasha. Tree: lvs. ovate, or ovate-oblong, acute, rounded at the base, with 10-15 pairs of veins, 3-5 in. long: cones about 1 in. long, solitary on a peduncle 1/2-1 in. long. Japan. S.I.F. 2:12. CH
- A. fruticosa, Rupr. (A. viridis var. sibirica, Regel). Allied to A. viridis. Shrub: lvs. broadly ovate or elliptic-ovate, usually rounded at the base, nearly doubly or sinuately serrate. Siberia, Corea. CH
- A. hirsuta. Turcs. (A. incana var. hirsuta, Spach). Allied to A. tinctoria. Tree; young branchlets, and petioles tomentose: lvs. suborbicular to elliptic, acutish, denticulate and slightly lobed, ferrugineously tomentose beneath. Japan, Manchuria. CH
- A. jorullensis, HBK. Allied to A. acuminata. Lvs. oblong-lanceolate, coarsely dentate. Cent. Amer.CH
- A. mollis, Fernald. Closely allied to A. crispa. Shrub or small tree: branchleta pubescent: lvs. pubescent beneath. 2—4 in. long. N.E. Amer., west to Lake Winnipeg, south to Mass.CH
- A. nitida, Endl. Tree, to 100 ft.: lvs. ovate to ovate-oblong, short-acuminate, not plicate, 3-4 in. long, entire or remotely serrulate, bright green and lustrous above, glabrous: male catkins very slender, to 6 in. long: cones 2-4, peduncled. Himalayas. B.M. 7654.CH
- A. oblongifiolia, Torr. Tree, 20-30 ft.: lvs. oblong-ovate, cuneate, doubly serrate, 2-3 in. long: strobiles 1/2-1 in. long, peduncled. N. Mer. and Aris. S.8. 9:457.CH
- A. occidentalis, Dipp.==A. tenuifolia.CH
- A. orientalis, Decne. (A. barbata, Hort., not C. A. Mey. A. firma, Hort., not Sieb. & Zucc. A. macrophylla, Hort.). Allied to A. cordata. Tree: lvs. ovate-oblong, obtusely or crenately serrate, 2-5 in. long, glabrous, with 8-10 pairs of veins: cones ovoid, glutinous, 1/2-1 in. long; nutlets without wing. Asia Minor.CH
- A. pubescent, Tsch. (A. glutinosa X incana). Lvs. roundish-ovate or obovate, irregularly serrate, pubescent beneath. Natural hybrid.CH
- A. rhombifolia, Nutt. Tree, 60-80 ft.: lvs. cuneate, oval or ovate, 2-3 1/2 in. long, finely serrate, yellowish green and puberulous beneath: strobiles oblong, peduncled. W.N. Amer. S.S. 1):450.CH
- A. Sieboldiana, Mats.==A. firma.CH
- A. sinuata, Rydb. (A. sitchensis, Sarg.). Allied to A. viridis. Shrub, 3-16 ft.: lvs. slightly lobed, serrulate, glabrous, thin. W. N. Amer. 8.8.14:727.CH
- A . Spaethii, Callier (A. japonica X subcordata). Tree: lvs. ovate-lanceolate, sharply serrate, violet-purple when unfolding. Of garden origin.CH
- A. subcordata, C. A. Mey. Tree, 30-50 ft.: lvs. ovate or oblong- ovate, rounded at the base, 2-6 in.-long, crenately or doubly serrate, glabrous or sometimes pubescent beneath: cones about 1 in. long: nutlets with a narrow wing. Caucasus.CH
- A. tenuifolia, Nutt. (A. incana var. virescens, Wats. A. occidentalis, Dipp.). Small tree, occasionally 30 ft.: lvs. ovate, 2-4 in. long, slightly lobed and double serrate, green and nearly glabrous beneath. W. N. Amer.CH
- Alnus AlnobetulaCH
- Alnus aureaCH
- Alnus barbataCH
- Alnus communisCH
- Alnus cordataCH
- Alnus cordifoliaCH
- Alnus denticulataCH
- Alnus firmaCH
- Alnus glaucaCH
- Alnus glutinosaCH
- Alnus imperialiaCH
- Alnus incanaCH
- Alnus incisaCH
- Alnus japonicaCH
- Alnus laciniataCH
- Alnus maritimaCH
- Alnus MitchellianaCH
- Alnus oblongataCH
- Alnus oreganaCH
- Alnus oxyacanthifoliaCH
- Alnus pendulaCH
- Alnus pinnatififaCH
- Alnus pyrifoliaCH
- Alnus rotundifoliaCH
- Alnus rubraCH
- Alnus rubrinerviaCH
- Alnus rugosaCH
- Alnus serrulataCH
- Alnus tiliaceaCH
- Alnus tiliaerfoliaCH
- Alnus tinctoriaCH
- Alnus undulataCH
- Alnus viridisCH
- Alnus vulgarisCH
- Alnus yashaCH
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963