Sunday, April 4, 2010

The World of Rubiaceae and Pavetta wallichiana

Brilliantly white and elegantly erect, the flowers of the Pavetta wallichiana herald their presence against the shadows of the rain forest interior and, like little trumpets, serenading the greatness of its family Rubiaceae. Why? Well, for one, Rubiaceae is the biggest family of trees in Malaya and has members in such significant number and diversity in the understory that their presence and density is a measure of the intactness of the rain forest on a whole.

So, seeing Pavetta and other rubiaceous shrubs is good news. The forest has a healthy measure of composition indicative of minimal disturbance, or showing sign of regeneration, at the lower strata. In fact, in climax condition, the forest teems not only with rubiaceous trees and shrubs, but a whole kaleidoscope of fascinating herbs, climbers and epiphytes such as Hydnophytum formicarium, an ant plant. Rubiaceae happens to be the fifth largest family of flowering plants in the world too.

However, the fascination do not stop there at the grand level; Pavetta wallichiana gives us an insight into the microcosmic niche of bacterial association. This is what E.J.H. Corner described in the Wayside Trees of Malaya: "The species of this genus are interesting because there occur in the little oblong, dark green, thickened flecks or warts on the leaves nitrogen-fixing bacteria like those on the roots of leguminous plants and Casuarinas. As a consequence, Pavettas are said to give a rich manure and to be useful as a cover-crop under shady conditions".

Close-up of warts below.

The useful bacteria are pass into the seeds and into the next generation of plants and the association remains unbroken. (Photo of fruit below)

Such is the wonder of Rubiaceae and Pavetta wallichiana. : )