Fruiting of Bush Grape Cayratia mollissima

posted in: Plants | 4

The flowering of the Bush Grape (Cayratia mollissima) was posted HERE. It was then flowering profusely, attracting bees that helped pollinate the flowers.

Cayratia mollissim -fence-fr [wyc]

Now two months later the plants have covered my chain link fence fronting the main road (above). The flowers have developed into fruits that are fast turning pink on ripening (below). Indeed the plants make an attractive cover, the fruits attracting curious passersby.

Cayratia mollissim -fence-fr [wyc]

So far the ripe fruits failed to attract birds, squirrels or any other wild animals (below).

Cayratia mollissim -old fr [wyc]

Even ants were not interested in the fruits, although they taste sweet. Leaving some ripe fruits near a column of ants attracted some that came near to investigate but apparently were uninterested (video below).

Another video below similarly shows that ants were definitely not interested in the fruit or its juice. When some sugar solution was placed near the fruit, ants swarmed around the sugar, ignoring the fruit juice.

The fruits were left in the open for a week but remain uneaten with mynas and squirrels around most of the time. And at night the Common Palm Civets (Paradoxurus hermaphroditus) are regularly around but ignored the fruits when placed along their foraging path.

So far nothing seems to be attracted to the fruits except some curious passersby. Two men plucked the unripe, faintly pink fruit each and popped it into their mouth. Another ate a ripe fruit. I don’t think they would do it again the next time they pass by.

Unripe fruits are packed with calcium oxalate crystals, probably raphides. These needle-like crystals penetrate the soft tissues of the buccal cavity causing intense pain. The image below shows three bundles of raphides from another plant – Dumbcane (Diffenbachia sp.) as seen under the microscope. The individual needles can be seen shooting out from two bundles when the leaf was sectioned.

dieffenbachia-caoxyalte-crystals

Ripe fruits on the other hand cause less pain as there are less raphides in them. I did bite into a ripe fruit. The juice was sweet but when it made contact with my throat, it caused some pain, I suppose not as intense as with juice of the unripe fruits.

I managed to trace an article on the internet written by a experimental cook. She used the unripe fruits called kanakalyte in Kannada, Karnataka, India. The green fruits were boiled twice and strained to dissolve the calcium oxalate thus making the fruits edible. She cooked them with spicy coconut, dried chillies and garlic. The dish had a strong flavor but went well with the spices. The recipe can be found in the above link.

YC Wee
Singapore
19th September 2016

4 Responses

  1. How interesting! So even the ripe fruits may cause a sore throat? How are this fruit’s seeds dispersed then, if no creature will eat it?

  2. Right now I have no idea. Maybe a bird, not seen in my area, is the dispersal agent?

  3. Meiliana K. Tansri

    Thank you for this article. I’m from Jambi, Indonesia, and spotted this plant on a roadside. The owner said they were poisonous, but my, those pink fruits are pretty! I’ve been searching for the information for months, using my entire taxonomy knowledge (mostly from high school biology, haha) until fortunately I stumbled into your article. Very useful. Thanks again.

    • It is irritating to the throat as the attractive fruits have needle-like crystals that irritate the buccal cavity. Eating a fruit is not as bad as munching on the stem of Dumb Cane (Dieffenbachia spp.). In olden days slaves were forced to chew on the stem of this Dumb Cane as a punishment. The mouth will swell and the slave will be unable to talk, suffering from the pain for hours until the effect wears off, thus the name dumb cane.

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