374 



Betulaceae 



beneath or glabrous except for axillary tufts of brown hairs, 

 the lateral nerves of 7 to 12 pairs, the petioles 1-3.5 cm. long, 

 usually glabrous; fruiting aments 2-3.5 cm. long, 8-10 mm. 

 in diameter, short-cylindric to oblong, erect, the scales 6-8 

 mm. long, ciliolate, the midlobe linear-lanceolate, the lateral 

 ones nearly orbicular, ascending, 1/3-1/2 as long as the mid- 

 lobe; nuts broadly obovate, puberulous above, 2-3 mm. long, 



the wing narrower than the nut. June-July. Mountains; 



Hokkaido, Honshu (centr. and n. distr.), Shikoku; extremely 

 variable.- Kuriles, Sakhalin, Kamchatka, and Korea. 



Van japonica (Shirai) Koidz. B. bhojpatra var. japonica 



Shirai; B. ni\oensis Koidz. Nagaea-no-dake-kamba, Naga- 



BA-NO-SHiRA-KAMBA, Ma-kamba. Leaves deltoid-ovate, the 

 lateral nerves of 14 to 15 pairs, the fruiting scales with a nar- 

 row midlobe and rather spreading lateral lobes. Honshu 



(centr. distr. and Kanto Distr.). 



Var. subcordata Koidz. Aka-kamba. Leaves shallowly 

 cordate. Occurs with the typical phase. 



8. Betula tatewakiana M. Ohki & S. Watanabe. Yachi- 

 kamba. Branching shrub about 1 m. high; branchlets 

 pubescent while young, soon becoming glabrous, very densely 

 glandular; leaves coriaceous, ovate or obovate, 1.2-3 cm. long, 

 1-2 cm. wide, acute at both ends, acutely serrate except on 

 the lower margin, glandular and hairy beneath, especially 

 on the nerves, the petioles 2-6 mm. long, pilose; fruiting 

 aments erect, axillary, oblong-cylindric, 1-1.5 cm. long, 3.5- 

 7.5 mm. across; bracts sparsely pilose on back, 3-lobed, ciliate, 

 2.8-4.2 mm. long, 2.7-3.4 mm. wide, the lobes subequal; 



nutlets obovate or elliptic, 3 mm. long, winged. Bogs; 



Hokkaido (Tokachi Prov.) ; rare. 



9. Betula apoiensis Nakai. B. miyoshii Nakai; B. miiji- 



mae Nakai Apoi-kamba. Much-branched shrub about 



1 m. high, the branchlets densely resinous-glandular, short- 

 pubescent while young; leaves ovate to broadly so to ovate- 

 orbicular, 1.5-4 cm. long, 1-3 cm. wide, acute, usually rounded 

 at base, irregularly acute-toothed, with silky-pubescence be- 

 neath while young, glabrescent, sometimes persisting only on 



the nerves, the petioles 2-10 mm. long; fruiting aments erect, 

 subglobose to short-cylindric, 1-3 cm. long, 6-12 mm. in 

 diameter, short-pedunculate, 2-5 mm. long, the scales 3-4 mm. 

 long, glabrous, ciliolate, the midlobe lanceolate to ovate, the 



lateral lobes obovate, shorter than the midlobe. Hokkaido 



(Mount Apoi). 



10. Betula globispica Shirai. Jizo-kamba, Inubushi. 

 Tree with whitish peeling bark, the branchlets grayish or 

 yellowish brown, scattered pilose while young; leaves broadly 

 ovate, 4-7 cm. long, 3-5 cm. wide, short-acuminate, irregu- 

 larly mucronate-toothed, rounded to broadly cuneate at base, 

 smooth, slightly lustrous, soon becoming glabrous above, long- 

 pilose on nerves beneath, the lateral nerves of 8 to 10 pairs, 

 the petioles 5-15 mm. long, slightly pilose; fruiting aments 

 ellipsoidal to subglobose, 2.5-3.5 cm. long, the scales 13-15 

 mm. long, the lobes narrowly lanceolate, obtuse, ciliolate, the 

 lateral lobes ascending, 1/2-2/3 as long as the midlobe; nuts 



3-4 mm. long, broadly obovoid, with very narrow wings. 



Mountains; Honshu (Kanto and centr. distr.); rare. 



11. Betula grossa Sieb. & Zucc. B. ulmifolia Sieb. & 

 Zucc; B. carpinijolia Sieb. & Zucc, non Willd.; B. solennis 



Koidz. Yoguso-minebari, Azusa, Mizume. Tree, with 



dark gray smooth bark, the branchlets yellow-brown and 

 scattered long-pilose while young, becoming glabrous, chang- 

 ing to chestnut-brown; leaves rather thin, ovate, 5-10 cm. long, 

 3-6 cm. wide, acuminate, shallowly cordate to nearly rounded 

 at base, acutely toothed, dull, nearly glabrous or scattered long- 

 pilose above, pilose on nerves beneath, the lateral nerves of 8 

 to 14 pairs, the petioles 1-2.5 cm. long, pilose; fruiting aments 

 sessile or nearly so, ellipsoidal to oblong, 2-2.5 cm. long, 12-15 

 mm. in diameter, the scales ciliate, 6-7 mm. long, the midlobe 

 narrowly oblong, obtuse, the lateral lobes ascending, elliptic, 

 about half as long as the midlobe; nuts ovate, about 2 mm. 



long, the wings slighdy narrower than the nut. Mountains; 



Honshu, Shikoku, Kyushu. The branches have a characteristic 

 odor when broken. 



5. ALNUS Mill. Han-no-ki Zoku 



Deciduous trees or shrubs; leaves alternate, pinnately nerved, toothed, rarely entire, sometimes shallowly lobed; staminate 

 aments elongate, usually pendulous, with 3 flowers in the axil of each bract, the perianth-segments usually 4; stamens 4; pistillate 

 aments short, globose to short-cylindric, conelike, the densely imbricate scales slighdy woody, persistent and with 2 flowers in 

 the axil of each scale, the perianth absent, the bracteoles adnate to the bract (scale) ; ovary sessile, 2-locular, the ovules solitary 



in each locule; styles 2, cylindric; nuts flat, sometimes laterally winged. More than 30 species, in the N. Hemisphere and S. 



America. 



lA. Winter-buds sessile, with 2 or more unequal scales; pistillate aments with protective winter bud-scales; staminate aments sessile, soli- 

 tary; flowering with the leaves. 

 2 A. Leaves narrowly ovate, with 12-26 pairs of lateral nerves. 



3 A. Aments usually from the lateral buds, the pistillate solitary; branches glabrous, rather stout; leaves with 12-15 pairs of lateral 



nerves I. A. sieboldiana 



3B. Aments from the terminal and lateral buds near the top, the pistillate lateral, 1-6 in a group; branches usually pilose while 

 young. 



4A. Leaves with 13-17 pairs of lateral nerves; pistillate aments paired, sometimes solitary, erect 2. A. firma 



4B. Leaves with 20-26 pairs of lateral nerves; pistillate aments 3-6 in a group, nodding l. A. pendula 



2B. Leaves broadly ovate, with 10-12 pairs of lateral nerves 4. ^. maximou/kzii 



IB. Winter-buds short-stiped, with 2 or 3 nearly equal scales; pistillate aments naked during the winter; staminate aments more or less 

 pedunculate; flowering usually before the leaves. 

 5A. Leaves plicate in bud, broadly elliptic to ovate-orbicular or obovate-orbicular, shallowly incised on the upper margin to emarginate, the 

 lateral nerves nearly parallel and straight. 

 6A. Leaves ovate-orbicular to broadly elliptic, obtuse to acute, rounded to subtruncate at base, often glaucescent beneath. 



5. A. hirsuta 



