JARS v45n4 - Rhododendron keiskei

Rhododendron keiskei
Frank Dorsey

Reprinted from the Vancouver Chapter newsletter, Nov. 1989

In the April and October newsletters we looked at R. augustinii and R. oreotrephes , both typical and better known members of the Triflora subsection. In this month's newsletter we will discuss a lesser known and more unusual Triflora...R. keiskei.
The species is named after a prominent Japanese botanist, Keisuke Ito (1803-1901). He is said in the Rhododendron Handbook to have been its "discoverer". As R. keiskei is widely distributed from Central Japan southwestward to Yakushima, the term "discoverer" is open to question. Keisuke Ito may have introduced the plant to the West, although Davidian (in his Rhododendron Species, Volume I, Lepidotes ) states that it is described by Miquel in 1866 and not "introduced" until 1908 (after Ito's death).

R. keiskei
R. keiskei

R. keiskei was given an Award of Merit by the Royal Horticultural Society in 1929 and the currently popular clone 'Yaku Fairy' was given a similar award in 1970.
While the RHS Handbook gives R. keiskei's height as "up to 6 feet", this must be looked upon as extreme and highly unusual. Cox in his Smaller Rhododendrons suggests three divisions: the prostrate form from Yakushima, the dwarf form and the taller, more common (in the wild) form.
The first listed is by far the most popular in cultivation. While the name 'Yaku Fairy' refers to a particular clone, unfortunately the name is used indiscriminately when referring to prostrate forms. Other than to the purist it doesn't really matter, as all of the prostrate forms are most attractive. 'Yaku Fairy' reaches only about 20 cm (8 inches) in height but spreads out to much greater dimensions.
The dwarf form, of which Warren Berg's 'Ebino' is an example, is taller than the prostrate form and although not generally as attractive a plant, has the advantage of being hardy. (All keiskeis are, however, winter hardy in our area.)
Cox's third category embraces the "leftovers", variable in form and foliage but taller than either of the preceding categories.
Unlike most other Triflora, R. keiskei comes in only one colour - yellow. The yellow admittedly varies in intensity from pale to lemon yellow. It would appear that the dwarf and prostrate forms have the deeper colour. The flowers are occasionally single but more often are in trusses of two, three or as many as six. They are not of heavy substance but in the low growing forms are reasonably long lasting.
The prostrate form is eminently suited for the front of a border or for a rock garden. It makes a good year around plant in any location where its foliage and tight compact form can be displayed to advantage.
Browsing through any up-to-date catalogue of rhododendrons you will notice the number of dwarf hybrids which have keiskei 'blood' in them - 'Patty Bee', 'Princess Anne', 'Golden Bee', 'Mary Fleming', 'Shamrock' and 'Wren' all come to mind.
R. keiskei , in particular in the prostrate form, is well worth growing. Although you are not likely to find it in the run-of-the-mill garden centres, it can usually be ferreted out at the few nurseries specializing in rhododendrons or at our own sales.