Pterygodium dracomontanum flowers

The flowers of Pterygodium dracomontanum grow in a many-flowered, dense and erect raceme of about 13 cm long. The pale green bracts below each flower are borne erectly, tapering to their acutely pointed tips without becoming reflexed below open flowers. The bracts may be keeled, especially near their broad bases and covered in glistening surface cells as in the photo.

The sepals are green in various shades across the geographical distribution of the species, dull dark green in the photo. They turn black over time. The petals, positioned on the flanks of the dorsal sepal are green, as is the lip with a purple tinge added; the lip appendage usually bright green.

The sepals are broad, rounded with concave inner surfaces and curving in. The lip, attached to the column, is thick and roundly ovate, its appendage shield-like with blunt lobes that spread (not recurve) and has a stalk-like base; the lip covers the anther. Flower size is 15 mm by 7 mm.

Pollination is mainly done by oil-collecting bees: the plants secrete this oil instead of nectar but it fulfils the same function by enlisting insect support for pollination. At least two Rediviva bee species, viz. Rediviva brunnea and R. neliana have been observed pollinating this orchid. These and other oil-collecting, South African bees, have the mutualistic servicing relationship with certain flowers, including orchids. Instead of gathering nectar like most bees, they collect floral oils, which they use for nesting and feeding their larvae. The bees harvest the oil from host flowers by rubbing their forelegs against oil-secreting trichomes. Trichomes are hairs, glandular hairs, scales or papillae. 

This is another evolutionary solution among the many interspecies survival pacts found throughout nature. Maybe oil significance is more widespread at levels not appreciated by people earlier. The way these mutual benefits are enjoyed on a durable basis by bee and an orchid are exemplary. Evolution continues to craft miracles of cooperation in the land of the living. The higher-level living might learn from this and aim for cooperating a little faster.

Flowering of this species happens from late spring to early autumn. The photo was taken during January (Liltved and Johnson, 2012; Steiner and Whitehead, 1991: Oil Flowers and Oil Bees: Further Evidence for Pollinator Adaptation. Evolution, 45(6), pp. 1493-1501; iNaturalist; Wikipedia).