i8 PRESENT-DAY GARDENING 
R. Brookianum, R. multicolory and i?. Malayanum. Judging 
by herbarium specimens^ there are many more than these 
with strong claims to the attention of horticulturists. Under 
cultivation they have proved to be too tender to thrive 
in the ordinary greenhouse^ subtropical conditions being 
necessary for them. A useful race of perpetual-flowering 
hybrids and seedlings has been raised from the several 
species named above. They cross freely with each other, 
but all attempts to breed a hybrid between this and either 
of the other sections of the genus have so far failed. 
NORTH AMERICAN 
There are sixteen species of Rhododendron in North 
America, one of which, R. maximumy the Rose Bay, is 
arborescent. The other evergreen species are R, cali- 
fornicunty R. macrophyllumy R. punctatumy and R. catawhiensey 
the last named being one of the parents of the popular 
garden race of hardy sorts. It grows on the summits of 
the Alleghany and Appalachian mountains, often forming 
dense thickets through which the traveller can make his 
way only by following old bear paths. Here also grow 
some of the deciduous Azaleas or Swamp Honeysuckles, 
such as R. arhorescenSy R. calendulaceuniy R. nudiflorumy and 
R. viscosum. These colour wide stretches of country when 
they are in flower in May or June. In an account of a 
trip in June 1892 to the Roan Mountain in North Carolina, 
Professor Sargent gives the following particulars of R. 
catawhiensey which was then in bloom : Along the borders 
of the forest, sometimes scattered individually and often in 
broad masses, covering hundreds of acres, the Rhododendron 
grows, mixed with bushy plants of the Mountain Alder. 
