Plant of the Week 01/16/2006: Sea Lavender (Argusia gnaphalodes)

Plant of the Week 01/16/2006

Argusia gnaphalodes (L.) Heine

Photographed by: Chelsie Vandaveer
Credits: Sea lavender photographed on Coco Cay, Bahamas.
Other Information: Olympus C-8080wz

Up from the beach lie the primary dunes. The wind and waves build and shift and sometimes destroy these dunes. Unstable, the primaries recruit pioneers, mostly grasses, salt-tolerant and with fibrous roots that trap and hold the shifting sands.

Back from the primaries are the secondary dunes. Vegetation has stabilized the sands. The sands are not as salty, but are still nutrient-poor and fast draining. It is a scrub habitat. Plants living on dunes must tolerate high amounts of solar radiation, infrequent moisture, and almost constant winds.

Sea lavender (Argusia gnaphalodes (L.) Heine =Mallotonia gnaphalodes (L.) Britton) is a tall ground cover/small shrub of the scrub zone of east central Florida through the Keys, the West Indies, and Central America. Worldwide, there are five species of Argusia. The genus is a member of the Boraginaceae, the forget-me-not family.

The species epithet, gnaphalodes, derives from the Greek, gnaphalon, a "lock of wool". The leaves are pubescent, fuzzy. The dense plant hairs slow the rate of transpiration, the loss of water from the leaves, and protect the leaves from strong solar radiation.

Sea lavender flowers most of the year with a peak bloom during winter. The flowers are borne on a helicoid cyme—arranged on one side of the branching (facing upward). The branches uncurl with the bottommost flowers opening first. The flowers open white and turn pink—on any one cyme, the flowers will range from pink to white.

Sea lavender produces drupes, single-seeded fruits. Unlike the typical drupe (i.e. cherries, olives), sea lavender's are corky fruits. The seeds can blow out to sea and drift to other lands.

In Florida and on larger islands, sea lavender is in eminent danger of extirpation (extinct in parts of the historic range) due to housing and commercial development near the beaches.

(Compiled from: "Mallotonia gnaphalodes", Edward F. Gilman, Fact Sheet FPS-379, Cooperative Extension Service, IFAS, University of Florida, Oct. 1999; "Native Shrubs for South Florida", Alan W. Meerow, EES-59, Florida Energy Extension Service, IFAS, University of Florida, July 1991; "Sea-lavender, Sea-rosemary" Gann, G.D., M.E. Abdo, J.W. Gann, G.D. Gann, Sr., S.W. Woodmansee, K.A. Bradley, E. Verdon and K.N. Hines. 2005. Natives For Your Neighborhood, Institute for Regional Conservation, Miami; "Argusia gnaphalodes", Wunderlin, R. P., and B. F. Hansen. 2004. Atlas of Florida Vascular Plants [S. M. Landry and K. N. Campbell (application development), Florida Center for Community Design and Research.] Institute for Systematic Botany, University of South Florida, Tampa.)