BETULACEAE. — BBTULA 487 



Belula alha, siibspec. latifolia, var. knmtschatica Regel in Bull. Soc. Nat. 



Mosc. XXXVIII. pt. 2, 401, t. 7, fig. 1&-20 (1865); in De Candolle, Prodr. 



XVI. pt. 2, 165 (186S). 

 Belula pendula, var. japonica, f. typica Schneider, III. Handh. Laubholzk. I. 



113, fig. 62 q2 (1904). 

 ? Betula japonica, var. resinifera Winkler in Engler, Pfianzenr. 1V.-61, 79 



(1904). 

 Betula alba, var. vulgaris Shirasawa, Icon. Ess. For. Jap. II. t. 11, fig. 19-37 



(1858). 



A typo praecipue differt foliis saepissime plus minusve tenuioribus, basi trun- 

 catis V. late cuneatis, rariiis subrotundis, raargine inaequaliter acutius serrato- 

 dentatis, saepe breviter lobulatis, subtus in axillis nervorum paullo barbulatis, 

 rarius etiam ad ner^'os laxe sericeis, petiolis fere semper glabris. 



NORTHEASTERN ASIA. Kamtchatka : without locahty, Rieder & Stewart 

 (type, ex Regel) . S a g h a I i e n : Odomari, thickets, common, August 6, 1914, £^. H. 

 Wilson (No. 7355; bush or small tree, 1.5-5.4 m. tall; probably a distinct form, the 

 lateral lobes of the bracts being very erect ; fruits). 



JAPAN. Hokkaido: prov. Shiribeshi, Otaru, May 1, 1890, K. Miyabe 

 (flowers); prov. Ishikari, Sapporo, Mt. Moiwa, September 18, 1892, C. S. Sargent 

 (sterile); Kamikawa, July 1905, U. Faurie (No. 6630; fruits, large and thick 

 catkins) ; in sylvis Jirafu, June 26, 1905, U. Faurie (No. 6634; fruits); "basi 

 vulcani Tarumai," July 1905, U. Faurie (No. 6635; fruits). Hondo: prov. 

 Shimotsuke, round Yumoto, on Senjo-ga-hara, October 19, 1914, E. H. Wilson 

 (No. 7669; slender tree, 8-20 m. tall, girth 0.3-0.9 m., bark pure white, common, 

 fruits pendulous; fruits) ; round Lake Chuzenji, alt. 1600-1800 m., common, woods, 

 moors, May 26, 1914, E. H. Wilson (No. 6767; slender tree, 6-20 m. tall, girth 

 0.3-1.2 m., bark white; flowers); Komagatake, July 1905, U. Faurie (No. 6G31; 

 fruits); prov. Shinano; above Narai, alt. 1100 m., September 3, 1905, J. G. Jack 

 (fruits); Kawanakazami, July 16, 1884 (ex Herb. Sci. Coll. Univ. Japan; fruits). 



It is as difficult to separate the typical B . japonica Siebold from the variety kamt- 

 schatica as it is to distinguish both from var. mandshxirica Winkler, because there 

 are undoubtedly many intermediate forms. There is great variability in the shape, 

 texture, dentation and pubescence of the leaves as well as of the bracts. The 

 leaves of the type are always more or less pubescent, at least on the under side of 

 the midrib, and are more or less distinctly bearded in the axils of the veins below. 

 In forms like the type of var. pluricostata Winkler the petioles are slightly villose, 

 but other specimens show the same pubescence, texture and dentation, differing 

 only in the size of the leaves and in the less numerous lateral veins which are 

 mostly 6-9, rarely 9-12 in number. 



B. japonica Siebold as a whole seems to be somewhat intermediate between the 

 European and western Asiatic B. alba Linnaeus sensu lato and the North American 

 B. papyrifera Marshall and its nearest allies. The forms of the subsect. Albae from 

 northern Asia and from North America need a thorough investigation. 



Betula japonica occurs in fair numbers on the high mountains of Shinano 

 province in central Hondo. It is common as a small tree in the Nikko region and 

 increasingly so to the northward; in Hokkaido and Saghalien it is abundant. It 

 is a tree of moderate size with thin sj)reading branches and pure white bark. 



Pictures of this Birch will be found under Nos. x275, x279, x301, x381, x414 

 of the collection of my Japanese photographs. E. H. W. 



Betula japonica, var. mandshurica Winkler. See p. 461. 



