Tucked into the northern edge of the Malesian rhododendron bed at MEMBG is a very fine specimen of Blakea gracilis Hemsley, a melastome (Family Melastomataceae). This handsome, evergreen species hails from montane tropical forests in Central America. The UCLA specimen originated from a cutting taken in 1978 at 2300 meters on the southwestern slope of Volcán Barba, Provincia Heredia, in Costa Rica. The species is relatively unknown to horticulture and does not appear in the two principal lists of woody plants, Sunset's Western Garden Book and the Royal Horticultural Society's Dictionary of Gardening, so it probably will be our responsibility and pleasure eventually to make this plant available in the trade.
Our specimen is a shrub two meters tall, but in the wild this species lives as a hemiepiphyte, a plant that begins life as an epiphyte and later may become rooted in soil, forming a small tree to twelve meters in height. Blakea therefore is at home with many of the Malesian species of Rhododendron, which also are epiphytes in tropical montane forests. This growth habit does well in our soil mix of bark chips, coarse Perlite, and coarse peat moss.
The opposite, decussate leaves tend to form on short upright shoots, so that the entire branch appears to be somewhat one-sided, like dogwood (Cornus). The short-petioled leaf is up to ten centimeters in length. The blade is elliptic to obovate in shape, and both bright green surfaces are fairly glossy, completely lacking hairs (glabrous). Blakea leaves exhibit the characteristic arcuate design of the longitudinal primary veins ("nerves") found in nearly all members of Melastomataceae and rarely elsewhere in the plant kingdom. In B. gracilis, there are three prominent primary veins extending to the leaf tip and an additional fainter vein along each smooth (entire) leaf margin. The very thin, mostly parallel cross veins (between the nerves) appear flat and dark on the lower surface.
Blakea flowers are solitary. Each is produced on a shoot, with two pairs of leaves (bracts) located just below the flower. In bud, the overlapping portions of the flower petals are pink, but they open as a flat, white flower about five centimeters across. There are six separate, lopsided (asymmetrical) petals--an unusual number for a dicotyledon, which generally has four or five. In the center of the flower is a circle of a dozen stamens, with the white filaments twisted to one side and the twelve yellow anthers grouped toward the middle as if pulled by a drawstring. The white style of the pistil emerges on the lower side. When the petals and stamens fall away, the observer can see a peculiar raised collar (hypanthium) and a persistent flat rim attached to the top of the urn-shaped, inferior ovary. Although no fruits have formed on our specimen at MEMBG, we have been successful in cloning this plant using cuttings. We have not yet attempted intentional pollination, to replace the pollination by mice that has been reported for this genus.
Arthur C. Gibson
Garden Director