40 THE AZALEAS OF THE OLD WORLD 



This is the Mountain or Hill Azalea (Yama-tsutsuji) of Japan, where it is abund- 

 ant from Yaku-shima in the extreme south to central Hokkaido in the north. Its 

 altitudinal range is from sea-level to about 1600 m., though north of the Nikko 

 region it is much less. In May and June by the wayside and on the hills and 

 mountain-slopes it is most conspicuous with its wealth of brilliant red flowers. It 

 grows among grasses and in thickets, also on the edge of forests and among the 

 undergrowth in thin woods, but it is a sun-loving plant and is seen to best advantage 

 in open thickets on mountain-slopes. The height is from 1 to 3 m., but averages 

 from 1 to 1.5 m., and according to situation it may be densely or laxly branched and 

 form either a broad or a narrow, twiggy bush. In the warmer parts of Japan all 

 the summer leaves and often some of the large spring leaves are persistent, but in 

 the colder parts they are both deciduous. The spring leaves vary in shape from 

 lanceolate or lanceolate-ovate to elliptic, and in size from 1.5 to 6 cm. in length 

 and from 0.8 to 3 cm. in width, and they may be either acute or obtuse; the summer 

 leaves are elliptic to obovate in shape, as is usual in the group to which this plant 

 belongs. The pubescence on the shoot, leaf, calyx, ovary and fruit varies in color 

 from pale gray to rufous. Typically the color of the flowers is red, usually bright 

 red, but it varies considerably and, excluding the forms to be mentioned later, 

 may be any shade from flesh-color to bright red. In size the flowers vary some- 

 what but average from 2.5 to 4 cm. across. The corolla-lobes are rounded or 

 pointed. The calyx is normally well-developed and the lobes are green, ciliate and 

 usually rounded, and from suborbicular to elliptic or ovate in shape, and from 2 to 

 8 mm. long; usually they are from 2 to 4 mm. long and occasionally they are scarcely 

 noticeable. The stamens may be included or exserted and this considerably affects 

 the appearance of the flowers; the anthers vary in color from pale yellow-brown to 

 blackish purple. The fruit is woody, erect, ovoid and from 0.6 to 1.5 cm. high, and 

 when open the valves are recurved for about one-third their length. 



In its typical form this variety, with its relatively large clustered flowers each 

 with five stamens, cannot be confused with anything else, but there are interme- 

 diate forms which inextricably link it with R. obtusum. The extremes look widely 

 different, yet on analysis size alone remains, and in this there is every gradation 

 both among the leaves and flowers. The degree of persistence of the leaves, which 

 is dependent upon winter temperature and exposure, strongly affects the appearance 

 of the plants. The leaves, flowers, genital organs and fruit vary in size, and the 

 flowers, anthers and pubescence vary in color. Round the base of Nishi-Kirishima 

 the typical red-flowered var. Kaempferi is plentiful; on the middle and upper slopes 

 of the mountain the typical f . japonicum abounds. In my ascent of this moun- 

 tain and after exhausting every means I could think of I failed completely to dis- 

 cover where one variety ended and the other began. The transition was both 

 gradual and complete. At my request my colleague, Alfred Rehder, has critically 

 examined the mass of material in our possession and is in complete agreement as 

 to the specific identity here set forth. I confess that I should much prefer to keep 

 Kaempfer's Azalea as a species distinct from R. obtusum, but the facts as I inter- 

 pret them will not permit of this. Whether var. Kaempferi or the f . japonicum 

 is best entitled to be considered the phylogenetic type of the species is difficult to 

 determine, but the first named is much more widely distributed, and north of 

 Hamamatsu, in prov. Totomi, central Hondo, is the only representative of the 

 species. 



Kaempfer's Azalea was first introduced to the Occident by Professor Sargent, 

 who sent seeds of it from the Nikko region and elsewhere in Japan to the Arnold 

 Arboretum in the autumn of 1892, where plants flowered in May, 1897. It has 

 proved both hardy and amenable to cultivation here, and in late May and early 

 June of each year flowers abundantly, producing most vivid and spectacular floral 



