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What Are the Functions of Octopus Tree Spines?

The octopus tree (Didierea trollii) is a distinctive, shrubby plant native to Madagascar that exhibits long, cactus-like stems with prominent spines. Meant to keep animals from consuming its precious water stores, the spines function much as cactus spines do. Scientists have discovered that this plant has DNA sequences similar to cactus and may in fact have evolved from New World cacti.
  1. Description

    • The octopus tree is true to its nickname, with bizarre, tentacle-like, fleshy branches that grow wildly into the air. The stems are completely covered with sharp spines that provide protection from animals. Ultimately the branches may reach 15 to 30 feet into the sky, although the trunk itself remains stubby and short. The leaves are small, growing to about .8 to 1 1/2 inches long. This plant comes from a small family native to Madagascar's spiny thickets in the dry, southwest region of the country.

    Functions of Spines

    • The needle-like projections of octopus tree spines jut straight out and grow in masses on the tree's branches, threatening any creature seeking the moisture-rich stores within. The spines are so sharp that they can tear human flesh. They are an evolutionary development also seen in other spiny thicket species.

      The spines may exhibit a green or white color and contrast with the rounded, green leaves surrounding them on branches. Like all succulents, Didierea trollii stems store water to survive the droughts that occur in the region where it lives. Water is a precious commodity in Madagascar, making its succulent stems appetizing to many creatures -- many of which no longer live in the region. The sharp spines immediately turn away any thirsty predators.

    Growth Habit

    • As the plant grows, the rising stems produce horizontal branches that grow close to the ground for many years. Small, green leaves grow on the stems, and large projectile spines develop early in the plant's life. Leaves will fall from the plant during the dry season to help the plant conserve moisture. In cold months, the plant enters dormancy and slows its growth.

      While the odd growth habit of this species is not often seen, it has a few relatives that exhibit similar traits. Also native to Madagascar thickets, the Madagascan ocotillo, bears similar resemblance, with spiny stems that jut out from a central trunk-like stem.


    • Provide the same care for this plant as is necessary for succulents and cacti. Well-drained, somewhat sandy soil containing moderate organic nutrients is ideal. Place it in full sun and allow plenty of space for the plant to grow laterally along the ground. Water it moderately, particularly when plants are growing. In winter, growth slows; cease watering during this time. Do not be surprised if foliage drops from the plant during periods of drought. Propagate by sowing seeds or taking stem cuttings.