Species of the Week
Number 6 -- July 10, 2006

In the Species of the Week feature of the Wildwood Web we took a close look at one of the species that lives in Wildwood.  To see the earlier featured species check the Species of the Week archives.

Long-leaved Houstonia Houstonia longifolia Members of the genus Houstonia are found only in North America, from Canada to Mexico.  The genus is divided into two groups.  In one group the plants are very short and have single blue flower per stalk.  These plants are known as bluets.  In the other group the plants are a little bit taller and have a branched inflorescence or flower cluster of pale violet flowers.  These plants are known as houstonias.  All members of the genus have four-parted flowers with the petals fused into a trumpet at the base.  The fruit, which is rarely noticed, is a small dry capsule that splits open to release the seeds.  Long-leaved houstonia can be identified by its long, narrow, opposite leaves. The genus Houstonia was named in honor of William Houston, a Scottish botanist who collected plants in the Caribbean and Mexico in the early 1700's.  He sent many specimens back to Europe and Linnaeus, who invented the system of scientific names, named the genus in his honor.  The species name, longifolia, comes from Latin for "long leaves."

Another species of houstonia, H tenuifolia, narrow-leaved houstonia, is very similar to long-leaved houstonia, differing in the size of the leaves and flower stalks, and the degree of branching.  This species has been reported from our area.  However, some botanists suggest that both supposed species are just variations on the same species.  The Digital Atlas of the Virginia Flora at Virginia Tech notes that in the Appalachian mountains plants intermediate between the two supposed species can be found.  This is a common situation in nature; plants are what they are, and it is humans that try to pigeonhole them into species, genera and families.

The genus Houstonia is in the Rubiaceae, the Madder Family, a family of mostly tropical plants.  Coffee and quinine are important commercial products that come from members of the Rubiaceae.  Perhaps the best known ornamental in this family is the gardenia. 

Long-leaved houstonia is found from Maine to Saskatchewan, south to Arkansas, Mississippi and South Carolina.  It prefers dry open woods and hillsides, especially with gravelly soil.  There is a nice little colony of this plant along the Grand Staircase that leads up from Wildwood drive on the east slope of the park.  Look for it as you walk down Wildwood Drive or climb the Grand Staircase.

GGC