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 figs).  Underneath the  calyptrate bud covers the young Ficus elastica fig also has a pair of thin bracts. The bud covers tend to be brown and hairy.

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 red bracts covering the young figs are also about to fall off (cauducous). The fig fruits at the base  are almost mature adult figs. The calyptrate bud covers fell off some time ago and do not appear in the photo. 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 calyptrate bud covers just about to fall 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