I am considering changing the name of this column to What's Wrong in the Garden. On a recent buying trip I learned we had goofed again. The plant we have labeled Seaside Heliotrope, Heliotropium curassavicum, is actually Pineland Heliotrope, Heliotropium polyphyllum (see photo).
The Online Atlas of Florida Vascular Plants lists three species of Heliotropium as occurring in this area. One is Scorpionstail, Heliotropium angiospermum. This plant can grow up to 3 feet in height, bearing small white flowers in terminal curved spikes that bloom year round. It is distinguished from the other Heliotropes by the leaves with petioles (stalks, stems). To confirm the identification, look for the two 2-sided nutlets where the flowers have gone to seed.
The other two Heliotropium should be quite easy to distinguish, I say should because I have never actually seen Seaside Heliotrope despite what the sign in the garden says. However, according to the Guide to the Vascular Plants of Florida the leaves of Seaside Heliotrope are smooth and succulent (think Aloe), while the leaves of Pineland Heliotrope are thin and paper like. Both can have white flowers and are low-growing. The Floristic Inventory of South Florida Database Online indicates that Seaside Heliotrope has been found in Gasparilla Island State Park but does not list it for Charlotte County. The Online Atlas lists vouchered plants from Charlotte County but I could not find the location or the date of collection.
Pineland Heliotrope has paper thin leaves and white or yellow flowers we commonly see along the roadside. It is worth noting that Taylor's Guide to Florida Wildflowers (1992) does not include this plant. The flowers may be white with a small or large yellow center or entirely yellow. The white-flowered form tends to grow as a creeping groundcover; never standing much taller than 12 inches while the yellow-flowered form is more upright and can reach several feet if left unpruned.
None of our local native plant nurseries carry Seaside Heliotrope so keep a look out for it, especially if you are near Gasparilla Island State Park.
References:
Scorpionstail, Heliotropium angiospermum
http://www.florida.plantatlas.usf.edu/Plant.aspx?id=2273
http://www.regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Heliangi
Pineland Heliotrope Heliotropium polyphyllum
http://www.florida.plantatlas.usf.edu/Plant.aspx?id=1024
http://www.regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Helipoly
http://hawthornhillwildflowers.blogspot.com/2010/01/pineland-heliotrope-heliotropium.html
Seaside Heliotrope Heliotropium curassavicum
http://www.florida.plantatlas.usf.edu/Plant.aspx?id=2291
Wunderlin, R. P. and B. F. Hansen: Guide to the Vascular Plants of Florida, 2nd ed., Gainesville, FL : University Press of Florida, 2003, p.352.
Floristic Inventory of South Florida Database Online, South Florida, Lee County, Heliotropium curassavicum http://regionalconservation.org/ircs/database/plants/PlantPage.asp?TXCODE=Helicura
Taylor, W. K. The Guide to Florida Wildflowers. Lanham, MD: Taylor Trade Publishing, 1992. p.. 317.
Photo by Karen Griffin