PLANT OF THE WEEK

Dr. T. Ombrello - UCC Biology Department

 

IMPATIENS

 

Common names:   

Busy Lizzy, Patient Lucy, Patience Plant, Sultana, Zanzibar Balsam, Impatiens  

Scientific name:        Impatiens Wallerana     (formerly Impatiens sultanii)

Explanation of scientific names:         

Impatiens  - from Latin, referring to the sudden bursting of the ripened pod like fruits when touched

Wallerana  - commemorates Waller

sultanii       - commemorates the Sultan of Zanzibar

Impatiens Wallerana is one of over 500 species of Impatiens in the Balsam family (Balsaminaceae).  The genus Impatiens has practically a world-wide distribution, with members ranging from the tropics and subtropics of Asia and Africa to the temperate zones of North America.  Close relatives of Impatiens Wallerana with which a gardener might be familiar would include the old fashioned annual Garden Balsam (Impatiens balsamina) and the 2 common wildflowers called Jewelweeds or Touch-me-nots (Impatiens capensis and Impatiens pallida).

Impatiens Wallerana is native to East Africa.  Its center of origin is Zanzibar, but it also grows naturally from Tanzania to Mozambique.  The plant grows as a succulent herb to a height of about 3 feet.  It thrives in rich moist soil and prefers a shaded or semi-shaded location.  It is a perennial in its native habitat, but since it cannot tolerate frost it is grown as an annual in this country.  Flowers are one to two inches across and come in a variety of colors, including carmine, pink, reddish-orange, purple, white, and variegated (a combination of white and some color).  An interesting floral feature is the slightly curved nectar spur protruding down from the back.  The nectar spur produces and contains a sweet sugary solution that attracts certain animals to serve as pollinators.  Moths and butterflies, with their elongated tube-like mouthparts, can reach the sweet nectar in the Impatiens flower spur and are the primary pollinators of the genus.  Hummingbirds can also be found visiting the flowers.

The Impatiens fruit is a capsule which, when mature, contains cells with a high internal pressure (turgor pressure).  In addition, the ripened fruit has structurally weak cells found in specific locations.  This combination of high pressure and weak cells allows for the slightest jarring of the plant to cause the fruit to "explode", shooting the seeds several feet from the parent plant.  This insures good seed dispersal and lessens the chance of an overcrowded seedling population developing around the parent.

While Impatiens Wallerana has long been available to the gardener as a flowering annual that will tolerate shade, it was never popular until the mid 1960's.  Varieties available before then did not flower consistently, and plants grown from a seed packet produced everything from dwarfs to vigorous but tall and lanky plants.  Many produced more stems and leaves than flowers. 

Starting in the mid 1960's, plant breeders focused considerable time and attention to hybridizing and selecting Impatiens Wallerana.  As a result of their efforts, there are currently dozens of cultivars available with a wide range of plant size and flower color.  They flower early and continuously through the growing season and are tolerant of heat.  Some cultivars can even grow in a full sun location.  Primarily due to these new introductions, the popularity of Impatiens has increased tremendously. 

The future for Impatiens looks even brighter.  In 1969, the U.S. Department of Agriculture and Longwood Gardens sponsored a plant collecting expedition to New Guinea.  The plant explorers literally stumbled across some new species of Impatiens with larger flowers, more intense color, interesting leaf patterns of variegation, and tolerance to bright sunlight.  These new species, however, were tall and lanky in habit, dropped their lower leaves early in life, and flowered sporadically.  Other plant explorers found similar species in Java and the Celebes Islands of Indonesia.

While none of these new species could be interbred with the Impatiens commonly grown in this country, the new species could be crossed with each other.  The USDA in Beltsville, Maryland and Longwood Gardens in Kennett Square, Pennsylvania initiated breeding programs with these "New Guinea Impatiens".  Since then, promising breeding lines have been released to seed companies and commercial plant propagators.  They, in turn, have introduced them to the general public.  These “new” Impatiens have become increasingly popular with home gardeners.  While some New Guinea Impatiens can be grown from seeds, as are Impatiens Wallerana, the offspring tend to be quite variable, with little uniformity.  For that reason, New Guinea Impatiens are propagated primarily from cuttings, making them more expensive.  Plant breeders are actively working on the development of consistent, seed-grown New Guinea Impatiens.  They are probably only a few years away from being released.

Impatiens, in general, are the most popular bedding plants in the United States, and will undoubtedly remain so for many years to come.

A flower on an Impatiens Wallerana plant growing in one of Union County College's greenhouses.