Toxic Sap Protects Tree Seeds

photograph of fruit in a hura crepitan tree

Biological Strategy

Sandbox tree

AskNature Team

Image: Cerlin Ng / Flickr / CC BY NC ND - Creative Commons Attribution + Noncommercial + NoDerivatives

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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The fruit of Hura trees is protected from predators by a highly toxic sap.

“The hura tree protects its explosive fruits with a sap so toxic that it will raise great red welts if it touches human skin and even blind those who get it into their eyes. The macaws, however, are not put off. Long before the fruits are ripe, the birds rip them apart, pods, seeds and all, and then, after a meal that would have poisoned others, they fly to particular places on a river bank where they can gnaw out and swallow a special clay which detoxifies their meal.” (Attenborough 1995:32-35)