Croton punctatus — Gulf Croton

A fully mature, densely branched plant about three years old. It is approximately 2.5 feet tall and about 3.5 feet wide.

Croton punctatus is an easily grown, but short-lived, shrub that reaches full maturity in 2–3 years and then begins a slow decline as it devotes itself to maximizing flowering and seed production. Its most distinctive feature is its leaves, which are densely coated with silvery scales resulting in leaves that vary in color from grayish green to silvery white. Young leaves have the densest coating of scales and can be so shiny and white as to appear to be made up of a metal such as aluminum. This is reflected in one of its common names, silverleaf croton.

A close-up of the leaves on a young, 6-month-old plant just beginning to flower.

Gulf croton naturally occurs in coastal strand and beach dunes along the Atlantic coasts of the Carolinas, Georgia, and Florida, from where it extends to the Gulf states and Cuba. It well lives up to its name, gulf croton, because it occurs along coasts nearly throughout the entirety of the Gulf of Mexico, from the western Florida coast to Texas and on to Mexico, Central America, and northern South America (Gann et al. 2016). In Florida, it has been recorded all along our coastline but it is apparently absent, or at least not recorded, from the Florida Keys, the coasts of mainland Monroe County, and Florida's west coast from Wakalla County to Pasco County (Wunderlin et al. 2016). Surprisingly, there are disjunct occurrences from the landlocked counties of Dauphin and Philadelphia in Pennsylvania (USDA 2016). All United States occurrences of gulf croton are in coastal counties except for the two Pennsylvania counties and Leon County in Florida and Brooks County in Georgia.

Its natural habitat provides clear clues to its cultivation and, as is the case with most beach-dwelling plants, it requires well-drained soil in a location where it receives full sun for most of the day. It is extremely drought tolerant once established but, for the healthiest, most densely branched, and beautiful plants, supplemental water should be provided during extreme or very long dry spells. In garden settings, it may be used as an accent plant or as a tallish groundcover. It is also useful as a small shrub in wildflower gardens or butterfly gardens where its fragrant flowers attract a wide variety of native flower-visiting insects. But gardeners must bear in mind that it is short-lived and it is rare for individual plants to last more than three or four years. Ample moisture produces big, beautiful plants but these tend to be the shortest lived, whereas plants grown under drier, leaner conditions tend to be the longest lived. However, declining plants are soon replaced by self-sown seedlings if the garden has open, sunny areas in which the seedlings can establish themselves. Propagation is by seeds or cuttings but seeds are difficult to gather because the capsules open ballistically and hurl the seeds far from the mother plant. I have never tried to grow gulf croton from cuttings because it abundantly self-seeds in my garden, but local native plant enthusiast, Ryan Leavengood, has had good success rooting cuttings of gulf croton in perlite and a rooted cutting from Ryan was the source of my original plant.

The flowers are not large or showy but they are reportedly fragrant and they attract a wide variety of insects. The flowers are either male or female but both genders are carried on the same plant.

Because it naturally grows in coastal strand and beach dunes, gulf croton is well adapted to the stressful environment of saltwater coasts and it is resistant to intense sunlight, strong winds, sand scouring, burial, high soil temperatures, low nutrient levels, and the occasional salt spray (Lonard & Judd 2009). As a consequence of its adaptation to life on sand dunes, it is valuable in coastal habitat restorations where it is an important element of the sand dune vegetation and helps to both form new sand dunes and reduce the erosion of established dunes.

Besides gulf croton and silverleaf croton, it is also known as beach-tea, which I assume is a reference to its previous use as a medicinal tea; however, I have not been able to locate any information on medicinal uses. Interestingly, Lonard & Judd (2009), who prepared a thorough review of Croton punctatus, were also unable to find any information on this plant's medicinal uses.

Note: Gulf croton is a true croton in the genus Croton, a large genus of about 750 species found nearly throughout the world but concentrated in the tropics and subtropics. The ornamental croton with variegated leaves that is a ubiquitous tropical landscape cliché, is in the same family but is a member of the genus Codiaeum.

A native bee visits the flowers of Croton punctatus. The flowers are attractive to a wide range of native pollinators.

References:

• Gann, G.D., M.E. Abdo, J.W. Gann, G.D. Gann, Sr., S.W. Woodmansee, K.A. Bradley, E. Grahl, and K.N. Hines. 2005–2016. Natives For Your Neighborhood: Croton punctatus. Institute for Regional Conservation. Link visited 8 June 2016.
• Lonard, R.I. and F.W. Judd. 2009. The biological flora of coastal dunes and wetlands: Croton punctatus Jacquin. Journal of Coastal Research 25(1): 23–29. doi: http://dx.doi.org/10.2112/07-0933.1
• USDA. 2007–2016. The PLANTS Database. Baton Rouge: United States Department of Agriculture National Plant Data Center. Link visited 8 June 2016.
• Wunderlin, R.P., B.F. Hansen, A.R. Franck, and F.B. Essig. 2016. Atlas of Florida Plants. Institute for Systematic Botany, University of South Florida, Tampa. Link visited 8 June 2016.

Image and text © 2016 Rufino Osorio

Manihot esculenta 'Variegata' – Variegated Cassava

Manihot esculenta 'Variegata' photographaed at the vegetable garden of Mounts Botanical Garden, where it was being grown as an ornamental accent plant.

Image and text © 2013 Rufino Osorio

Euphorbia thymifolia – Thyme-leaf Sandmat

Euphorbia thymifolia (synonym: Chamaesyce thymifolia) is an unassuming little annual native from Mexico to Argentina, the West Indies, and the paleotropics (Africa and Asia). It has been introduced in the Hawaiian islands and is considered by some to have been introduced in Florida, but the Atlas of Florida Vascular Plants lists it as native. I have observed it at three sites in Florida: (1) in pavement cracks in downtown Tampa; (2) near the mouth of a gopher tortoise burrow in a sandhill habitat in Tampa; and (3) in a highly disturbed old field that had originally been sand scrub at Jonathan Dickinson State Park in Martin County.

A young plant growing under very harsh conditions in a tiny crack in the street in front of my house.

As is the case with most annual, weedy spurges formerly in the genus Chamaesyce, it is very easily grown and, once introduced into a garden, you will likely have it forever. Although it can be a weed of potted plants, thus far it has not been a problem in the garden. Certainly, it is nowhere near as aggressive and abundant as the quadrumvirate of weedy spurges in my yard that can sometimes number in the hundreds: Euphorbia graminea, Euphorbia hirta, Euphorbia hypericifolia, and Euphorbia ophthalmica.

Images and text © 2013 Rufino Osorio

Spanish Daisy and Company

A Spanish daisy, Helenium amarum, made itself at home in my carport. It is a perky and pretty yellow annual daisy native to Florida. It is joined by two additional native annuals: slender three-seeded mercury, Acalypha gracilens, and partridge pea, Chamaecrista fasciculata. Rounding out this little micro-biome are two native perennial grasses (Paspalum species). One of the grasses is visible on the left side of the Spanish daisy and just a hint of the leaves of the second grass is visible at the extreme left of the photograph.

Image and text © 2013 Rufino Osorio

A Xeric Garden

A dwarf agave with rosettes less than 12 inches wide toughs it out in pure Florida sand. My guess is that it is one of the many forms of Agave potatorum. The genus Agave is native to the New World from the southern United States to South America but it reaches its greatest diversity in Mexico.

I have been watching the endeavors of a local gardener with keen interest. Apparently having grown weary of tending a lawn, this gardener removed all grass from a small front yard and is growing tough desert plants. Although markedly different from the typical pseudo-tropical south Florida garden, it shares with such gardens the presence of plants from far-flung regions of the world and a lack of any native plants.

Euphorbia tirucalli is native to Madagascar and is characterized by a highly toxic and caustic sap. It has also been linked with Burkitt's lymphoma, a typically rare cancer that tends to be associated with regions where Euphorbia tirucalli is extensively used as a hedge plant. The pictured plant is a cultivar with brightly colored new growth called 'Sticks on Fire.'

An Opuntia species with a growth habit similar to the native semaphore cactus (Opuntia corallicola); however, the native semaphore cactus is markedly spiny and tends to have pads of a lighter green color.

The so-called Madagascar palm is not a palm at all. It is Pachypodium lamerei, a spiny-stemmed succulent from Madagascar in the oleander family (Apocynaceae). It should be handled with care since the spines are extremely sharp and can cause severe injuries or infections if they happen to impale the knuckles or joints of the fingers.

This aloe is very similar to Aloe arborescens from Africa; however, the rosettes are much smaller than that species. I am guessing that perhaps it is a small-growing hybrid of Aloe arborescens.

Images and text © 2012 Rufino Osorio

Amelia's Smarty Plants

Jatropha integerrima is a drought tolerant shrub from Cuba in the euphorbia family (Euphorbiaceae). It is very common in south Florida gardens and is often recommended for butterfly gardens.

Amelia's Smarty Plants is a full service neighborhood garden center located at 1515 North Dixie Highway in Lake Worth, Florida (phone number: (561) 540-6330). Plants in stock are very diverse and include a wide variety of subtropical and tropical ornamental plants as well as flowering annuals, herbs, and a diverse selection of Floria native plants. Below are a few photographs that I took on a recent visit.

Justicia betonica, the white shrimp plant, is native to Africa and has unassuming flowers peeking out from white, green-veined bracts; however, the flowers apparently produce ample nectar since they are avidly visited by honeybees. Like many shrimp plants in the genus Justicia, it has plain green leaves and is vegetatively nondescript.

Nerium oleander 'Variegata' is a variegated oleander with brilliant chartreuse leaves that gradually develop varying amounts of green. The flowers are blousy pink things that I do not find particularly attractive. Oleander is now cultivated throughout the subtropics and tropics of the world but was originally native to western Asia and the Mediterranean region of Europe and northern Africa. Formerly regarded as non-invasive in the United States, it is now listed as invasive in Arizona and it is escaping to floodplains and riparian zones in California.

The pink trumpet vine, also known as Zimbabwe creeper (Podranea ricasoliana), is an African vine in the bignonia family (Bignoniaceae). It has escaped cultivation in a few counties in Florida. Such occurrences should be carefully monitored to see if, like many tropical vines, it has invasive tendencies.

This is a hybrid Tecoma and the flower color and flower form leave no doubt that it is in the same family (the Bignoniaceae) as the native trumpet creeper (Campsis radicans). And like the native trumpet creeper, it is attractive to hummingbirds. The genus Tecoma is native to both the New World tropics as well as to Africa.

Chrysanthemum ×morifolium, the garden chrysanthemum, was domesticated in China where it was originally used as a culinary herb and tea plant. It generally does not survive south Florida's hot and humid summers; however, many garden centers carry them as short-lived decorative flowering plants to brighten the autumn garden. The plant pictured here has pom-pom flowers, one of 13 classes into which chrysanthemum flowers are categorized.

This showy chrysanthemum with brilliant autumnal colors has semi-double flowers, another of the 13 classes into which chrysanthemum flowers are categorized.

Images and text © 2012 Rufino Osorio

Croton linearis – Pineland Croton

Croton linearis growing at Juno Dunes Natural Area in Palm Beach County, Florida.

Croton linearis is a small, evergreen shrub about 1.5–3 feet tall that is commonly known as pineland croton or granny bush. It is native to the Bahamas, Florida, Cuba, and Jamaica. In Florida, it is confined to the southeastern and extreme southern portions of the peninsula and has been recorded from St. Lucie, Martin, Palm Beach, and Miami-Dade counties, as well as the Florida Keys of both Miami-Dade and Monroe counties. In these counties, Croton linearis typically occurs in well-drained, dry, sandy soil near the coast or in rocky pinelands.

The wildlife value of Croton linearis is moderately high since its oily seeds are eagerly sought out by seed-eating birds and mammals; however, plants are either male or female and both sexes must be present for the seeds to form. Additional wildlife value is provided by the foliage, which is used as the caterpillar food plant of the critically endangered Florida leafwing butterfly, Anaea troglodyta floridalis.

Image and text © 2012 Rufino Osorio