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from the May 1, 2011 Newsletter issued from written at Mayan Beach Garden Inn 20 kms north of Mahahual, Quintana Roo, México
ICACO
On Wednesday morning some visitors needed to be dropped on the beach in Sian Ka'an so they could beach-hike for about ten miles, then be picked up later, so I rode up with Marcia, co-owner of Mayan Beach Garden. You can see Marcia standing beside the interesting bush found there at the top of this page.

In English the bush is called Icaco or Cocoplum. It's CHRYSOBALANUS ICACO, a member of the Chrysobalanus Family, little known to Northern nature lovers, because its approximately 460 species in 17 genera are restricted to the American tropics and subtropics. The family is close to the Rose Family.

The eye-catching feature about this bush was that it was loaded with plum-size, white fruits, as seen below:

The white one was mature and rather nice to eat. White, sweet, melon-textured flesh surrounded a large seed. If you're hot and hungry while hiking the beach, you'd welcome finding this bush heavy with fruits. In fact, I hear that the fruits make a fine jam.

Among the fruits there were a few tiny blossoms, such as those shown below:

That picture is interesting because it shows two blossoms side by side, but the flowers are different. The older, fading one at the left bears numerous male stamens -- the items with slender filaments (stems) topped with oval, pollen-producing anthers. However, on the younger flower at the right, there's no sign of stamens. In that flower's center you see a round-topped, pollen-receiving stigma atop a slender style leading down into the flower, to the ovary nestled there like an upright egg in a bowl.

Bearing two such different flowers is possible for Icaco because the bushes can be "hermaphroditic, or andromonoecious, or gynomonoecious." Hermaphroditic plants are those on which all flowers bear both male and female parts. Andromonoecious plants bear both bisexual and strictly male flowers on the same plant. Gynomonoecious plants bear both bisexual and strictly female flowers on the same plant. It looks as if our flower picture shows a plant that's gynomonoecious, because the flower on the right is strictly female, while the older flower on the left appears to bear both male and female parts.

I searched for studies explaining how such a curious sexual orientation could be adaptive for an organism, but it appears that no one really knows. Lots of theories, but no clear experimental results.

Icaco is native from Mexico to northwestern South America, as well as the Caribbean and tropical western Africa. It's been naturalized in several places in Asia and Oceania.