ABOVE: The long narrow (lanceolate) leaves of a juvenile Ficus binnendijkii from Kuala Belalong in Temburong, Brunei. Many species of plants in the Moraceae family (breadfruit/figs)  produce  different shaped leaves  in juvenile and adult plants. This is especially common  with the root climbing figs in Section Rhizocladus.

However  in Section Conosycea  (strangling figs) only two species are known to produce dimorphic leaves, F. binnendijkii and F. maclellandii.  In both cases the juvenile leaves are long and thin (lanceolate)  and the adult leaves are shorter and and more rounded. Berg (2011) Leaf dimorphy in F. binnendijkii and F. maclellandii.

Berg-(2011)-F.-maclellandii-and-F.binnendijkii-Berg-(2011)-2.jpg

Note that Berg’s  leaf illustrations clearly show strong basal veins in  both  the F. binnendijkii  leaves which are absent  from the both the F. maclellandi leaves.

03 Ficus binnendijkii Belalong Brunei lanceolate -L.1594619
A closeup of the leaf from a juvenile F. binnendijkii from Kuala Belalong in Brunei. Note the prominent pair of basal veins.

02 Ficus binnedndijkii Bogor L.1594680.jpg

01 Ficus binnendijkii lanceolate .jpg
Juvenile F. binnendijkii leaves from the Bogor Botanic Garden in Java.

Ficus binnendijkii Java -L.1594681.jpg

06 Ficus binnendijkii Atlas der Baummarten von Java (1906)
This illustration from Kooders & Valeton (2018) Atlas Der Baumarten von Java illustrates the typical adult leaf of F. binnendijkii in which the basal veins extend almost around the edge of the whole leaf. Compare with this photograph.
05 Ficus binnendijkii L.1594618 Sarawak .jpg
Ficus binnendijkii from the Bario Highlands in Sarawak. The leaves are intermediate  between juvenile and adult leaves.