According to Berg (2005) the following figs that grow in Borneo have “calyptrate bud covers” covering the young fig fruits: F. benjamina , F. binnendijkii, F. cucurbitina, F. consociata, F. elastica, F. forstenii, F. globosa, F. lawesii, F. subcordata, F. stricta.
But what is a “calyptrate bud cover” ? According to Corner’s (1978) diagram (below) a calyptrate bud cover is a pair of thin covers like a stipule that entirely surround the young fig fruit. (A stipule surrounds the young leaf bud in all fig species). Corner’s drawing (below) shows that underneath the calyptrate bud cover the young Ficus elastica fig also has a second layer of bud covers or bracts.
According to Zhang (2014) the purpose of Calyptrate bud covers may be to protect the young fig from parasitic fig wasps or to regulate the entrance time of pollinating fig wasps.