I was given a houseplant with a unique, square stem. New leaves come from the top of the plant, and it has small white flowers that appear at the base of each leaf where the leaf joins the stem. Any idea what this is called, and how I should look after it? Thanks!
Your looks like a Madagascar Jewel Plant (Euphorbia leuconeura). Here are some care instructions on how to grow a Euphorbea leuconeura (Madagascar Jewel Plant) as an indoor houseplant.
Light: bright indirect lightVery few houseplants should be placed in direct sun. High light refers only to bright indirect light since direct sun often burns the leaves of indoor houseplants. An area that is too hot and dry encourages Spider Mites and causes blooms to quickly fade. A northern exposure really doesn't provide enough light for high light plants. These plants need to be placed directly in front of an east-facing window, within 1-3 feet of a west-facing window, and within 5 ft. of a south facing window. A high light area has over 300 ft. candles of light., no direct sun.
Water: Water once a week, or when the top 50% of the soil has dried out, when a Euphorbia Leuconeura is actively growing in the Spring and Summer. Water every other week in the Fall and winter or less if the soil has not dried out.