November/December 2001 Exerpt

Excerpt from GLORY BOWERS by Rand B. Lee

If any group of ornamentals deserves its common name, it’s the glory bowers (Clerodendrum spp.), a genus of some 400 vines, shrubs, and trees native primarily to the tropics and subtropics. All bear clusters of showy blossoms—which in many of the species are sweetly fragrant—and feature rich green leaves arranged in pairs or whorls along their stems.

Viewed up close, each individual flower’s intricate construction is worthy of appreciation. They are composed of slender tubes of varying lengths, each ending in a rather pointed bud. The buds open into flattish, five-petaled trumpets from which multiple stamens protrude. In some species, a papery, petallike calyx of a contrasting color surrounds the base of the flower, creating a showy two-tone effect.

As you would expect from their tropical and subtropical ancestry, most cultivated glory bowers are very tender perennials primarily grown as house plants or conservatory specimens in North America. The evergreen vining species are borderline hardy outdoors even in USDA Plant Hardiness Zone 11, but some of the shrubby deciduous glory bowers are hardy to USDA Zone 8—or even 6 with protection—and can be grown outdoors as specimen shrubs or integrated into mixed borders.

VINING SPECIES

The first glory bower I ever encountered was bleeding heart vine (Clerodendrum thomsoniae), a twining vine native to West Africa that grew on an arbor my mother had built along the streetside of her home in Key West, Florida. Its leaf-pairs, which were big, green, and oval, formed a lush backdrop for a summer-long succession of cascading white bells that gradually opened to reveal tiny true flowers of pure, saturated crayon red. The blooms gave off no scent, but for once—I was and am a scentaholic—I didn’t mind. Sitting in their shade gave me the sense of being surrounded by a cloud of the valentines that gave rise to the vine’s common name.

Named for the wife of one Reverend W. C. Thomson, bleeding heart vine was discovered in southeastern Nigeria in 1860. Brought back to northern climes, it rapidly became popular among the Victorians, who raised it in heated greenhouses. Indoors, given full to part sun, it tends to flower most heavily in the spring, but sometimes reblooms sporadically in summer and fall. A selection with white-margined leaves, ‘Variegatum’, is sometimes offered.

Even showier than Mrs. Thomson’s glory bower is red clerodendrum (C. splendens), another west African climber that grows to 12 feet tall. Hardy only in Zone 11, it has shiny, dark green, oval to oblong leaves, paler beneath, and glorious scarlet-red-stamened blossoms borne in large, dense clusters at the ends of their branches. Though not fragrant, C. splendens can be the star of the winter windowsill, so long as you keep the temperature at 60 degrees Fahrenheit or above and give the plant full to part sun. It blooms in June and July in its native habitat, but indoors normally puts on its show in fall and winter.

A hybrid between bleeding heart vine and red clerodendrum, C. 5speciosum is a twining climber that grows to 12 feet tall. It has large, roundly spear-shaped leaves and red to scarlet flowers with prominent creamy stamens that extend out from white or pinkish calyces. Like its parents, C. 5speciosum will only thrive at temperatures above 60 degrees, and it has similar cultural requirements.

SEMI-HARDY SHRUBS

Not all the glory bowers are tropical. Among the hardiest species are deciduous shrubs such as C. bungei and C. trichotomum, which grow quite well in temperate gardens.

Native to China and northern India, C. bungei was discovered around 1820 by Russian botanist Alexander von Bunge. A suckering shrub, it can grow over six feet tall and wide, with reddish stems and large, dark purple-green leaves that have a musky scent—hence Bunge’s original name for it, C. foetidum. I find the dark pink, five-lobed flowers, which are held in rounded clusters, sweetly fragrant, so I was startled to read that some noses discern the aroma of roast beef. C. bungei is reliably hardy to Zone 8, but can be grown in Zone 7 with protection. It will grow best where it will be shaded from the worst of the afternoon sun in summer and watered regularly, but it has naturalized even in rather dry ground in the Houston area.


Members can view this article in its entirety by clicking here.