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

Sideroxylon tenax – Tough Bumelia

Tough bumelia is a common, thorny, deciduous or evergreen shrub or small tree native to North Carolina, South Carolina, Georgia, and Florida. It occurs nearly throughout Florida but is wholly absent from the Panhandle and the western portion of northern Florida. It is found in nature in dry, well-drained soils in full sun to light shade in sandhills, sand scrub, and coastal hammocks. The lower surface of the leaves are completely covered with a dense layer of silky hairs that varies from pale brown to a rich mahogany brown. This dense coat of hairs no doubt slows down the loss of water through transpiration and is an adaptation to the plant's xeric habitat.

Tough bumelia, like other Sideroxylon species, is a wildlife powerhouse since the dense, thorny branches provide protection for small birds and animals, the tiny white flowers attract an extremely wide variety of insect pollinators, and the dark, 1-seeded, olive-sized fruits have a gummy, but sweetish, pulp that is eaten by larger birds and various mammals.

In older works, tough bumelia is often listed as Bumelia tenax. Also, it is often described as being "spiny" but that is incorrect. Spines, in the strict sense, refer to modified leaves or their parts. Bumelia tenax is more correctly referred to as "thorny" since its sharp-pointed armature is derived from modified branches, not modified leaves.

Image and text © 2013 Rufino Osorio

Bourreria radula – Rough Strongbark

Rough strongbark is a Florida state-listed endangered plant with significant wildlife value. It is a large shrub or small tree with small, dark green leaves whose upper surface has coarse, rough hairs that give the leaves a sandpaper-like texture. Attractive and sweetly fragrant white flowers are borne nearly year around and these are much sought after by various insects, including bees and butterflies. The flowers are followed by rather large, highly ornamental, orange berries that are eaten by birds, raccoons, opposums, and other animals.

Rough strongbark occurs as a native plant in Florida only in the Florida Keys but it can be grown at least as far north as Palm Beach County and probably much further north if it is not grown too far from the moderating influence of the Atlantic Ocean or the Gulf of Mexico. Its cultivation presents few problems so long as it is provided with well-drained rocky or sandy soil and abundant sunlight. Once established, rough strongbark is extremely drought tolerant and even small plants have readily established themselves in the driest part of my garden. Propagation from cuttings and seeds is difficult; however, with time, numerous self-sown seedlings will appear under mature plants and these can be potted up when they are a few inches high. Since rough strongbark readily sprouts from the roots wherever the roots are cut or injured, it can probably also be propagated from root cuttings.

Rough strongbark is extremely tolerant of hot, dry conditions and poor, alkaline soils. Thus, it is useful as a landscape plant or hedge in difficult urban situations such as roadsides and parking lots. The abundant fruits falling on sidewalks can make quite a mess and it is not recommended as a residential street tree, although it is otherwise an excellent street tree.

Image and text © 2013 Rufino Osorio

Bastardiopsis eggersii – Jost Van Dyke's Indian-Mallow

Jost Van Dyke's indian-mallow is a highly endangered Caribbean shrub or small tree known from three islands in the British Virgin Islands and one island off the coast of Puerto Rico. An article by Fred Kraus provides very detailed information about this rare plant. The image above is of a young plant growing in a private garden in Fort Lauderdale, Florida. The plant is surrounded by numerous seedlings of black ironwood (Krugiodendron ferreum). The genus to which Jost Van Dyke's indian-mallow belongs has been a matter of some controversy and it is sometimes found listed as Abutilon virginianum or as Sida eggersii.

Plants in my garden flower in early spring (January in south Florida). The flowers are tiny but are attractive to bees and are rather pretty when examined closely.

Images and text © 2013 Rufino Osorio

Is Lantana depressa Sphingophilous?

Lantana depressa is a dwarf, evergreen, short-lived shrub that bears small but numerous bright yellow flowers. It is a state-listed endangered species that occurs only in Miami-Dade County. The flowers are attractive to butterflies and it is sometimes grown as a nectar plant in butterfly gardens.

On Tuesday, November 6, 2012, at approximately 5:30 PM (Eastern Daylight Saving Time) I was at the local Home Depot and noticed a large, brown sphinx moth repeatedly and persistently visiting the flowers of Lantana depressa. I purchased two plants and, after getting them home, I noticed for the first time that the flowers were fragrant. The fragrance was not powerful but it was distinct and clearly noticeable. It was sweet and pleasant but was unlike any other floral scent I have ever experienced. The next day, I tested the flowers to see if they were fragrant during the day but the scent was almost undetectable.

Based on these observations, it appears that Lantana depressa employs a dual pollinating strategy: psychophily (butterfly pollination) during the day and sphingophily (sphinx moth pollination) during the night. The presence of a distinct sweet odor that intensifies at night is a classic sign of sphinx moth pollination. Also, an adaption to sphinx moths as pollinators might explain an important distinction between Lantana depressa and the weedy, non-native, and invasive Lantana camara. The latter has flowers that open up one color and then fade to another. This allows pollinators to readily distinguish fresh, nectar-filled flowers from older flowers as well as creating a more easily noticeable floral display. In Lantana depressa, older flowers do not change color or else become merely a slightly darker shade of yellow. If Lantana depressa is transitioning to or has become adapted to sphinx moth pollination, this would explain the color constancy of the flowers since a difference in color between new and older flowers would not be perceptible to nocturnal sphinx moths.

Before ending this post, I would like to point out another interesting observation made at the Home Depot on November 6. Growing immediately adjacent to the pots of Lantana depressa were numerous cultivars of Lantana camara. The latter bore innumerable fruits in all stages of maturity whereas not a single fruit was to be seen on the plants of Lantana depressa. Although Lantana depressa will cross-breed with, and be genetically swamped by, Lantana camara, it appears as if that particular Home Depot clone of Lantana depressa was both self-sterile and not interfertile with the adjacent clones of Lantana camara.

Image and text © 2012 Rufino Osorio

Hibiscus poeppigii – Fairy Hibiscus

Hibiscus poeppigii is a dwarf, shrubby perennial that bears small 1-inch long brilliant red flowers pollinated by bees and hummingbirds. It will produce flowers all year round so long as warm temperatures and adequate soil moisture prevails. Plants in full sun grow 1–4 feet (0.3–0.9 meters) tall and about half as wide and bear leaves 1–2 inches (2.5–5 centimeters) long. The stems will grow taller and the leaves larger if plants are situated in the shade or are overtopped by taller plants.

Hibiscus poeppigii is readily propagated from seed which germinate in about 10 days if sown during warm weather. It makes a delightful pot plant and I have grown it from seed to flowering in about 4 months in an 8-ounce (0.24 liter) plastic cup. In the ground, plants will rarely exceed 1.5 feet (0.46 meters) tall and be rather twiggy and sparsely leafy if grown in a dry, sunny spot. Of course, plants will grow much taller and be more lush if grown in continually moist soil or in part shade. Since it is the smallest of all Florida native hibiscus, and because it begins to flower when scarcely 6-inches (15.24 centimeters) tall, it is referred to as fairy hibiscus, a name which I much prefer over the prosaic and literal common name of Poeppig's hibiscus.

Hibiscus poeppigii is a state-listed endangered plant in Florida, where it occurs only in Miami-Dade County and the Monroe County keys. It also occurs as a native plant in the Caribbean (Cuba and Jamaica) as well as in Mexico (from Tamaulipas to Yucatán and Chiapas) and Guatemala. Taxonomically, it belongs to section Bombicella of the genus Hibiscus. In the New World, the section is centered in Mexico and Hibiscus poeppigii is the only representative of section Bombicella that is native east of the Mississippi River.

Reference:

Fryxell, Paul A. 1980. A Revision of the American Species of Hibiscus Section Bombicella (Malvaceae). Science and Education Administration, United States Department of Agriculture Technical Bulletin No. 1624. Internet

Image and text © 2012 Rufino Osorio

Psychotria nervosa – Wild-Coffee

Wild-coffee is a member of the madder family (Rubiaceae), this is the same family to which coffee, ixoras, and gardenias belong. It is a common understory shrub in tropical to warm-temperate forests in northern and peninsular Florida from Duval County south to the Florida Keys. Wild-coffee is extremely popular as a landscape plant due to its beautiful, glossy, dark green leaves with deeply impressed veins. In addition, it is easily grown, adapts well to a variety of light and soil conditions, and it is extremely drought tolerant once established, especially if growing in the shade or in a partly shaded site. The tiny creamy-white flowers are insignificant but they are lightly scented and attract a diverse array of wildlife including native bees and both large and small butterflies. The flowers are followed by conspicuous red berries that are eaten by birds and mammals. From time to time, individuals with leaves variegated with white markings are encountered, either in the wild or among cultivated plants; however, thus far, such variegated-leaved clones have not been established in general cultivation.

Image 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

Lyonia lucida – Fetterbush

Lyonia lucida photographed at the High Ridge Scrub Natural Area in Palm Beach County.

Fetterbush, Lyonia lucida, is a common shrub throughout Florida and it has been recorded in every county in the state except Monroe and Suwannee counties. Besides Florida, it also occurs in Alabama, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Virgnia. It is found in bogs, cypress ponds, flatwoods, and scrub and is especially conspicuous in the spring, when it bears dainty small flowers that vary, depending on the plant, from very pale pink (almost white) to nearly red.

Image and text © 2012 Rufino Osorio

Dryas octopetala – White Mountain Avens

Michael Compagno snapped the images above in Alaska of Dryas octopetala, which is commonly known as white mountain avens. A member of the rose family, it is a plant of cold boreal and arctic regions and it extends south from Alaska through Canada and into the United States by growing down the chain of western mountains. Each tiny, seedlike fruit, technically referred to as an achene, is equipped with a long feathery tail that aids in catching the wind and helps to disperse the seeds to new locations. These images were captured in August and it was the middle of autumn in Alaska. Thus, very few plants were in flower but many were in fruit. If Michael had visited earlier, he would have been greeted by many dozens of pure white flowers, held a few inches off the ground, and resulting in a spectacular display. The flowers face the sun and the petals form a little bowl that concentrates the sun's rays and raises the temperature of the central part of the flower several degrees above the ambient temperature. Thus, keeping its pollinating insects cozy and warm.

USDA Distribution Map

© 2011 Michael Compagno (images) and Rufino Osorio (text) (exclusive of the USDA map).

Dodonaea viscosa – Varnish Leaf

Plant in flower. © 2007 by Forest and Kim Starr. Used under a Creative Commons license.

Dodonaea is a small genus of approximately 70 species of woody shrubs or small trees with alternate (or rarely opposite) simple or pinnate leaves. About 60 species are confined to Australia, about nine more occur in Africa, the Americas, and Asia, and one species, Dodonaea viscosa, is pantropical and occurs as a native plant on all continents except Antarctica and Europe. In Florida, Dodonaea viscosa is known as varnish leaf, a reference to the shiny, sometimes sticky, resinous coating on the leaves. It is remarkablly adapted to harsh coastal environments where it tolerates moderate salt spray, wind-blown sand, strong winds, and intense sunlight. Although usually growing as a small shrub up to 3 meters (10 feet) tall, in Hawaiian forests it is sometimes a tree up to 9 meters (30 feet) tall. Varnish leaf is characterized by alternate, simple, elliptic-shaped leaves; greenish flowers that are mostly either male or female on separate plants; and inflated, papery, 3-celled and 3-winged capsules that hold a few rounded, black seeds. The capsules are green when young, changing first to pale green and then gradually to various shades of pink, red, brick red, or purplish red, and eventually to light brown at maturity. Depending on growing conditions, temperature, and the plant's genetic background, the reddish color can be intense and may produce a highly ornamental effect.

Dodonaea viscosa is remarkable for its fast growth, general freedom from pests and diseases, and ability to thrive under highly varied conditions. In Florida, it is restricted to coastal strand and coastal hammocks but elsewhere in its range it grows in extremely diverse habitats. For example, in Hawaii it is found in "coastal dunes, lava fields, [and] dry, mesic and wet forests" (Anonymous 2009). Its altitudinal range in Hawaii is as impressive as the variety of habitats in which it occurs and it can be found in lowlands at 3 meters (10 feet) of elevation all the way up to subalpine shrubland at 2,347 meters (7,700 feet) (Little & Skolmen 1989). In the United States, in addition to to Florida, it occurs as a native plant in Arizona where it is described as "fairly common on dry, rocky slopes and in canyons, often on limestone" (Kearney & Peebles 1951:528). In California, it has been recorded from Orange County (USDA, NRCS 2010).

Drawing from Little & Skolmen 1989, a U.S. Government work (as republished by the University of Hawaii at Manoa 2003).

Varnish leaf is easily grown from seeds, although patience is required since germination rates may vary from a few weeks to several months. Propgation may also be effected from shoots with half-ripe wood taken in the summer (Plants for a Future 2010). Due to its rapid growth and ease of cultivation, varnish leaf is highly recommended for beginning gardeners in USDA plant hardiness zones 9–11 and it can generally be expected to succeed so long as it is provided sufficient water during establishment and is situated in an area with ample sunshine and well-drained soil. It is admirably suited for coastal gardens where many other plants find life difficult but it will also grow well inland. Due to its fast growth, evergreen leaves, and tendency to freely branch, it is perhaps most often used as a hedge or screen but it may also be profitably grown as a specimen plant, foundation plant, and in coastal and tropical hammock restorations. In addition to the wild form with bright green leaves, there is a popular purple-leaved cultivar that is extensively cultivated in the United States; however, plants of this cultivar that I saw in San Francisco seemed less vigorous than the green-leaved plants I am familiar with in Florida. Varnish leaf has very few faults only two of which are fairly serious. Occasional plants may become black from mildew growing on the sugary secretions of mealy bugs and scale but this situation is easily remedied by cutting the plant to the ground, after which it soon sprouts new, pest-free shoots that can attain their former height within a year. Another problem is that plants can become a big, floppy messs if provided with too much water or if planted in very rich soil.

Besides it ornamental uses, varnish leaf has numerous medicinal uses although such practices are not recommended since the leaves contain cyanogenic compounds, tannins, and saponins, all of which are toxic in sufficiently high quantities. The conspicuous capsules are both reminiscent of hops and have been used as a substitute for hops to add a bitter flavor to beer, thus accounting for another of its common names, hop bush. It is of considerable biogeographic interest in that it "and wingleaf soapberry ... Sapindus saponaria, are the only tree species native in both Hawaii and continental United States" (Little & Skolmen 1989).

References

• Anonymous. 2009. Native Plants of Hawaii: Dodonaea viscosa. University of Hawaii. Internet
• Kearney, T.H. and R.H. Peebles. 1951. Arizona Flora. Berkeley and Los Angeles: University of California Press.
• Little, Jr., E.L. and R.G. Skolmen. 1989. Common Forest Trees of Hawaii (Native and Introduced). Agriculture Handbook No. 679. Forest Service, United States Department of Agriculture (as republished by the University of Hawaii at Manoa, 2003). Internet
• Plants for a Future. 2010. Dodonaea viscosa. Internet
• USDA, NRCS. 2010. The PLANTS Database (http://plants.usda.gov, 29 August 2010). Baton Rouge: National Plant Data Center. Internet

© 2010, except as noted, by Rufino Osorio.

Asimina reticulata

The pineland pawpaws were magnificent this year and many plants were covered with flowers. This one was growing in a sand scrub nature preserve right smack in the middle of urban coastal south Florida approximately 10 minutes from my house by car.

© 2010 Rufino Osorio.