1921) REHDER, NEW SPECIES, VARIETIES AND COMBINATIONS 49 



least above the middle. From R. catawbiense the hybrid differs chiefly 

 in narrower more pointed leaves, in the glabrous rhachis, the glandular 

 not villose longer pedicels, the usually or often 6-lobed corolla, the sta- 

 men with whitish filaments, often 12 in number and the, at least toward 

 the base, more or less stipitate-glandular style, and in the usually 8- 

 celled ovary. It seems rather remarkable that the ovary even in the 

 flowers with ten stamens and a 5-lobed corolla should be usually 8-celled, 

 while in regard to the number of the corolla-lobes and the stamens the in- 

 fluence of R. discolor is less strong. 



Several forms have been raised, the one I consider the type of this 

 hybrid group has large flowers 8-9 cm. wide, of amaranth pink color 

 with a large blotch of partly confluent dots colored Pompeian red; the 

 corolla is usually 6-lobed, the lobes with undulate margin and the num- 

 ber of stamens 12; the anthers are large, ochraceous and apparently well 

 developed, the style is nearly glabrous, the leaves are generally oblong- 

 lanceolate. This form is distinguished as "Charles Sander." 



Other forms have light pink or nearly white flowers with fewer or al- 

 most no dots with the style glandular throughout or sparingly pilose 

 below the middle and with sterile anthers in one case; in one form the 

 leaves are broadly obovate to obovate-oblong. 



In its large open flowers this hybrid is similar to R. discolor Franch., 

 but it is hardier and for this reason a valuable addition to the number of 

 hybrid Rhododendrons adapted for cold regions. Though not as resistant 

 as the hardier hybrids of R. catawbiense, it has proved fairly hardy in the 

 neighborhood of Boston having stood the last two or three winters in 

 sheltered locations out-of-doors at Holm Lea and in the Arnold Arboretum 

 and has flowered this year in both places; R. discolor in the same localities 

 has suffered, and cannot be recommended for this latitude. 



Rhododendron obtusum var. arnoldianum (var. amoenum x var. 



Kacmpfcri), var. now 



This cross was raised at the Arnold Arboretum about 1910 from seed 

 of R. obtusum var. Kacmpferi Wils. fertilized by R. obtusum /. amoenum 

 Wils. It is exactly intermediate in habit, in size and color of the flow- 

 ers and in size, texture and persistency of leaves. From the var. Kacmp- 

 feri it is distinguished by the lower denser habit, smaller, darker and 

 more lustrous leaves, 2.5-4 cm. long, by the more numerous and broader 

 persistent summer leaves below the winterbuds and by the smaller flow- 

 ers 3-3.5 cm. across and in color between rosy mauve to nearly red (roso- 

 lene purple, rose color and rose dor£e according to Ridgway) and by the 

 shorter and broader sepals. From the f. amoenum the cross differs in 

 the more upright habit, the larger acute, usually less lustrous and thinner 

 leaves, in the less numerous and narrower summer leaves below the win- 

 ter-buds, by the larger flowers with a normal calyx, and the slightly 

 spotted corolla which is usually nearer to rose-color, rarely rosolene purple 

 as in f. amoenum. The seedlings show some variation in the size of the 



