Mucuna

Wiriadinata, H., Ohashi, H. & Adema, F., 2016, Notes on Malesian Fabaceae (Leguminosae-Papilionoideae) 16. The genus Mucuna, Blumea 61 (2), pp. 90-124 : 91

Mucuna and bats

Many Mucuna species have long inflorescences and flowers that are whitish, greenish or purplish, several species are said to have a disagreeable, musty flower odour. Inflorescences may be caulinascent. These traits have been associated with possible bat pollination (see Van der Pijl 1941). Van der Pijl (1941) did not observe bat visits, but observed on wing and keel petals typical claw marks that indicate bat visit. He also observed night flowering, the production of copious, sticky nectar and explosive pollen disposition (see also Dobat & Peikert-Holle 1985). Mucuna flowers are often quite sturdy, another requirement for bat pollination. A direct observation of bat visits was done by Hopkins & Hopkins (1993), who describe how a bat ( Synycteris australis (Peters)) alighted on an inflorescence of M. macropoda Baker f. , its position on the inflorescence, nectar eating and pollen disposition ( Hopkins & Hopkins 1993: f. 3, 4). Some traits in the pollen morphology of Leguminosae have been associated with bird- or bat pollination ( Ferguson & Skvarla 1982, Ferguson 1990).According to Ferguson & Skvarla (1982) especially exine sculpture and structure could be indica- tors of bird- or bat pollination. They mention coarsely rugulate to verrucate exine sculpture for species that are obviously bat-pollinated and the occurrence of tectal columellae or a double layer of columellae for some bird pollinated papilionoids. However, several genera and species adapted to bird- or bat pollination show no such specialisations and have perforate or finely reticulate exine sculpture. In 1984 Ferguson mentions verrucate ornamentation and complex exine stratification in some bird pollinated papilionoids. Stroo (2000) did not find any correlation between bat pollination and exine morphology. In his study only pollen size correlated positively with bat pollination: Pollen of bat plants is usually larger, 75 µm on the average, non bat-pollinated related species have significantly smaller pollen: 64 µm on the average. Pollen size seems also to be correlated with style length: In bat plants the styles are long, 52 mm on the average (range 4 – 240 mm), in non bat-pollinated relatives the average style length is 42 mm. In Asian Mucuna species the style length ranges from 12–150 mm, average c. 45 mm. Mucuna macropoda , a bat-pollinated species ( Hopkins & Hopkins 1993), has styles of 20 –21 mm long, while M. platyphylla (= M. albertsii ), according to Stroo (2000) not bat-pollinated, has styles of 60– 80 mm long. Probably style length cannot be used as a proxy for pollen size as an indicator of bat pollination.