A ripe female Ficus ruginervia fig at Long Pasia in south Sabah near the border with Kalimantan and Sarawak.

Ficus ruginervia is in Section Kalosyce. Section Kalosyce figs are root climbing lianas which grow up tall forest trees  closely attached to the trunk by numerous small roots. Typical Section Kalosyce figs have 3 types of leaves which differ in size and shape.  (1) Bathyphyll leaves which are small and non-symmetrical  and grow at the base of  the liana or on juvenile lianas and (2) Acrophyll leaves which  are larger, round and symmetrical  and  (3) Intermediate leaves  which are very variable combinations of the first two types. Acrophyll leaves only develop once the liana is fully mature and only grow on side branches once the liana finally reaches sunlight in the forest canopy above.

Photos and information provided by Shavez Cheema and Chun Xing WONG of 1Stop Borneo Wildlife.

The underside of typical bathyphyll leaves of Ficus ruginerva

The underside of typical bathyphyll leaves of Ficus ruginerva

Typical highly asymmetrical juvenile bathyphyll leaves  of Ficus ruginerva growing on a young liana.

Intermediate leaves of Ficus ruginerva  which in appearance are half way between the bathyphyll and acrophyll leaves.

Intermediate leaves of Ficus ruginerva  which in appearance are half way between the bathyphyll and acrophyll leaves.

Fully adult leaves of Ficus ruginerva. These acrophyll leaves are fully symmetrical.

Fully adult leaves of Ficus ruginerva. These acrophyll leaves are fully symmetrical.