NERVED FIG Ficus nervosa SECTION: OREOSYCEA
Latin: From the prominent side veins (nerves) on both the upper and underside of the leaf blade.
Habit: A large tree to 40 m with a straight white trunk and large buttresses at the base. As with the other figs in Section Oreosycea, there are no aerial roots or strangling roots.
Leaves: The leaves are very variable in size, dark green with a glossy upper surface. Note that trees from Sabah appear to have the largest leaves of any in the range. Both the side veins and the mid rib are clearly white. The veins on the under surface are prominent. The basal veins are variable with up to two prominent pairs. Herbarium collections dry brown in contrast to F. vasculosa leaves which dry greenish with a waxy sheen
Fig: The figs have peduncles (stalks) up to 1 cm and hang from the ends of the branches. There is usually a stipe an oblong extension of fruit body to which the stalk is attached. As with Ficus vasculosa the figs ripen yellow to bright red.
Sex: Monoecious (Bisexual) Both sexes combined in one plant.
Distinguish: Only 5 species of Section Oreosycea figs occur in Borneo. All have very tall straight white trunks with prominent buttresses at the base and no strangling or hanging roots. Apart from F albipila which is very rare only two Bornean Oreosycea have figs which ripen red, F. vasculosa and F. nervosa.
The leaves of these 2 figs are very different.
- With F. vasculosa the side veins are the same colour as the leaf whilst with F. nervosa the white side veins are prominent. The midrib is pale in both species.
- The basal veins are obvious in F. nervosa but obscure or absent with F. vasculosa.
- On average the leaves of F. nervosa are twice the length of F. vasculosa and have a long petiole (stalk) compared to a relatively short stalk with F. vasculosa. Note that the leaves of both species are very variable in size.
- The above differences result in dense dark crown for F. vasculosa trees and and a spreading, open, transparent crown for F. nervosa trees.
- The side veins of F. vasculosa reach the midrib at right angles ( close to 90 degrees) whilst with F. nervosa the angle is closer to 45 %.
Distribution: Rare in Borneo but locally common on the floodplain of the Lipad River at Tabin in Sabah as illustrated in the photo above.
Taxonomy: Berg & Corner (2005) recognize 3 subspecies;
(1) F. n. nervosa which is found from India to Taiwan. This sub-species is very closely related to F. magnoliifolia and possibly con-specific.
(2) F. n. minor confined to Sri lanka and India.
(3) F. n. pubinervis the sub species found from the Philippines, Borneo and Sumatra east to the Aru Islands near New Guinea
Range: Although uncommon in Borneo F .n. pubinervis is a relatively common tree in the seasonally dry forests of the Indonesian islands including Java. F .n. pubinervis was one of the first figs to colonize the bare volcanic cone of Rakata one of the Krakatau islands after the eruption of 1883.