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.

See Ficus elastica: Calyptrate bud covers 02.

02 Ficus elastica Corner (1978) - .jpg


02 IMG_1989
In the photo above the orange stipule on the growing bud is about to fall off  (cauducous). The second  (inner) layer of red bud covers covering the young figs are also about to fall off (cauducous). The fig fruits at the base  are almost mature adult figs.  Photo taken at the Dalit Golf Course, Tuaran, Sabah, Borneo of a fruiting Ficus elastica.


04 Ficus elastica IMG_1002.JPG
The brown objects covering these young figs just below the green stipule are the top (outer) layer of immature calyptrate bud covers  which expand and grow as the fig grows later turning bright red before falling off. Photo taken in Singapore.

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.

Zhang (2014) Purpose of Calyptrate bud covers on F. altissima