A Sensitive Plant and Common Weed

Mimosa pudica, also commonly called the sensitive plant was a popular houseplant when I was growing up in the 1970s. It was popular for its ability to quicky change shape by folding up its leaves to protect them from herbivore predators. At the slightest touch the plant is able to expell water from special cells in the leaves, changing the shape from frond-like to a stick-form. The plant creeps along the ground, never for than a foot or so in height. In tropical parts of the world this plant is considered and invasive weed.

Today, as I was treating plants to remove pests I happened to touch the leaves of a Mimosa pudica, one with a pretty puff-like flower. Sure enough, the leaves all folded up to almost nothing.

Mimosa pudica, the sensitive plant

Other more routine chores during my four-hour shift at the U of M Conservatory included cleaning three plants of Hibiscus clayi, native to Hawaii. These three plants in particular have suffered repeated infestations with a variety of insect pests. The staff are now suspecting the tropical room is too humid for them, they will be moved to a room with drier, more temperate conditions.

Hibiscus clayi, native to Hawaii

The most dramatic task for me today was pruning a large tree fern, Cyathea intermedia. The fronds of this tree are easily more than 10 feet in length and 3 feet wide. In the wild, the tree fern can reach more than 100 feet high. The tree is native to New Caledonia in the South Pacific.

Cyathea intermedia, tree fern

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