The appearance of hyacinths and crocuses, in late winter, is a welcome sight to gardeners and heralds the onset of geophyte season in the American Midwest. Geopyhytes are perennial plants that harbor underground, nutrient-storage structures that permit survival during periods of prolonged cold or drought and fuel the rapid development of stems, leaves and flowers when soil conditions recover.
There are three primary types of geophytes: those that produce bulbs, corms or tubers. Bulb plants, including hyacinths, tulips, narcissus, lilies, onions and others, possess a cluster of specialized leaf scales which surround the basal stem and store nutrients. In most species, a protective tunic envelops these scales and, in all species, a basal plate gives rise to the root system. Corms are starchy stem structures which sit vertically beneath the soil; crocuses and gladiolus species utilize this form of nutrient storage. Finally, tubers are thickened, starch-containing, horizontal structures along the roots or stems of certain plants; root tubers are found in dahlias and sweet potatoes while asparagus and strawberries harbor stem tubers.
While natural geophytes respond to local environmental conditions, usually blooming with the recovery from prolonged cold or drought, numerous cultivated species have been developed that provide garden color throughout the growing season. For example, most wild crocuses, native to Eurasia, bloom in the fall while their cultivated cousins ignite the first wave of spring fever here in the Midwest.
