Monday, July 23, 2012

Squarehead - Tetragonotheca helianthoides

Squarehead (Tetragonotheca helianthoides) occurs sporadically throughout the counties of the Florida Panhandle and south down the central peninsula to the latitude of Citrus and Lake Counties.  A small disjunct population also has been reported in Highlands County.  Throughout this range, it is found in sunny well-drained habitat types; especially sandhill and xeric flatwoods.  Squarehead is a species of the Southeastern Coastal Plain.  In addition to Florida, it is found from Mississippi and Tennessee, east to Virginia.
A deciduous perennial forb, squarehead dies to the ground each winter and emerges in early spring.  Its large, rough leaves are oval in shape, pointed, and with teeth along the margins.  They are opposite on the stem and clasp it. It forms multiple branches and individual stems can eventually reach about 3 feet tall. Plants may be at least 3 feet across.
Flowering occurs in late spring and early summer - making it one of the few truly early aster family species in our flora.  Individual flowers occur at the end of each stem.  The buds are large and enclosed by four sepals that give it a square shape and its common name.  The flowers are more than 1 inch across and rather showy.  Bright yellow ray petals surround a large central greenish yellow disc.  These attract a wide assortment of pollinating insects. Plants remain in bloom for many weeks.
Despite its many attractive features, squarehead is not commercially available from any nursery affiliated with FANN - the Florida Association of Native Nurseries.  We have been looking for a seed source for this wildflower for several years and recently were given seed by another plant collector friend who grows it in his Gainesville landscape.  If we are lucky, we will have some plants available by spring 2013.
Squarehead will tolerate partial shade, but performs best in mostly sunny locations with well-drained soils.  I have thought for a long time that this is one species deserving of greater landscape use. Hopefully, we are working toward that goal at Hawthorn Hill.

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