The morivivi (die-live) or sensitive plant (Mimosa pudica Linnaeus) was first described from South America. This unique plant is a short-lived subshrub, low-growing with long, vinelike stems. It is popular in the horticultural trade and has been introduced accidentally or intentionally to most tropical regions. Needing disturbed soils and full sunlight to establish, the sensitive plant is a nuisance species on agricultural lands outside its native range.

The delicate pink flowers are borne in a globular inflorescence; the flowers are both wind and bee pollinated. Each flower is capable of producing 2 to 4 seeds enclosed in a legume (pod). The inflorescence will produce numerous pods. The seeds are animal dispersed; the small pods have bristles which snag the fur or clothes of passers-by.

The sensitive plant is known for its thigmonastic (seismonastic) movements in response to touch; the leaflets and pinnae fold and the entire leaf collapses within seconds of the stimulus. The leaves also display nyctinastic or night-closure movements. Heavy wind, rain, dry spells, and heat cause similar movements. This response is controlled by the presence of a pulvinus at the base of each leaf. (See Weird Plants, October 25, 2001)

El Yunque, the Caribbean National Forest is a beautiful tropical rainforest in Puerto Rico. This year it is celebrating the one hundredth anniversary of its founding. To learn more about the plants, wildlife, and waterfalls, click on the link: http://www.southernregion.fs.fed.us/caribbean/