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Descurainia pinnata (Western tansymustard)
Photograph courtesy of J. Lotz, DPI

Ilex latifolia (Lusterleaf holly)
Photograph courtesy of Oregon State University http://oregonstate.edu

Lycium carolinianum (Christmas berry)
Photograph and copyright courtesy of Roger Hammer/Wildflowers of the Everglades, Atlas of Florida Vascular Plants

Persea humilis (Silk bay, scrub bay)
Photograph courtesy of Shirley Denton, Atlas of Florida Vascular Plants

Phoradendron leucarpum (oak mistletoe)
Photograph courtesy of Betty Wargo, Atlas of Florida Vascular Plants

Poinsettia heterophylla (Mexican fireplant, fiddler's spurge)
Photograph courtesy of Dennis Girard, Atlas of Florida Vascular Plants

Botany Section

Compiled by Richard E. Weaver, Jr., Ph.D., and Patti J. Anderson, Ph.D.

This section identifies plants for the Division of Plant Industry, as well as for other governmental agencies and private individuals. The Botany Section maintains a reference herbarium with over 10,000 plants and nearly 1,500 vials of seeds.

Descurainia pinnata (Walt.) Britt. (a genus of 40 species from temperate and cool regions, including Europe, South Africa and North America). Cruciferae (or Brassicaceae). Western tansymustard. This is a widespread, weedy, annual herbaceous plant, usually seen flowering in late winter or early spring, in turf, open fields and waste places with sandy soils throughout the United States and into Mexico and Canada. This species usually reaches a height of 25-50 cm, with single or multiple stems that often branch. The stem and leaves are gray pubescent, and the deeply dissected leaves are pinnatifid. The flowers occur in terminal racemes, each flower with four yellow, yellow-green or white petals. The fruits are narrow siliques, up to 15 mm long and 2-4 mm wide, on pedicels that can reach 1.5 cm in length. Seeds are less than 1 mm long. This is a variable species with several recognized subspecies. Native peoples throughout its range used the seeds as food, and some mixed the plant with iron pigments to prepare a dye. (Nassau County; B2009-62; Flewellyn W. Podris; 12 February 2009.) (Austin 2004; Murphy 1996; http://www.fs.fed.us/database/feis/plants/forb/despin/all.html.)

Ilex latifolia Thunberg. (a nearly cosmopolitan genus of approximately 400 species, particularly diverse in temperate and tropical Asia and America). Aquifoliaceae. Lusterleaf holly. This magnificent evergreen tolerates well the heat of summers in northern and central Florida, yet it is barely known and rarely planted here. It is native to Japan and has been in cultivation in this country since 1840. A dense, pyramidal tree to 10 m tall, it is texturally similar to Magnolia grandiflora. The leathery leaves are lustrous dark green above and yellowish beneath, oblong to elliptic with an abrupt, sharp tip, coarsely serrate but not spiny on the margins and 10-20 cm long. Like all hollies, male and female flowers are borne on separate trees (dioecious). The dark red fruits are about 8 mm in diameter, and they are borne in dense, axillary clusters that completely encircle the twigs. The fruits persist through the winter, if the robins and mockingbirds miss them, but the color generally fades considerably. The trees are difficult to propagate, perhaps partially explaining why they are so rare in cultivation. (Submitted by the general public; 6 January, 2009.) (Dehgan 1998; Dirr 1990.)

Lycium carolinianum Walt. (a genus of about 100 species of shrubs from warm temperate regions, primarily the Americas). Solanaceae. Christmas berry, Carolina desertthorn, lycium. This species is a spiny, salt-tolerant, evergreen shrub to 2 m tall, found in coastal areas, including shell mounds and the edges of salt marshes and brackish swamps, from South Carolina to Florida and west to Texas and Mexico. The clustered, fleshy, simple leaves grow up to 2 cm in length, have entire margins and are linear to narrowly oblanceolate. The flowers, growing singly, have a calyx with four lobes and a blue to lavender (sometimes pale enough to appear white) corolla with four fused petals. The fruit is an ellipsoid berry that turns bright red when ripe, usually in December. Although some species in this family contain toxins, there are some reports that the Christmas berry fruit is edible, like other members of the family, such as tomatoes and peppers. Without doubt, this species is an excellent food for wildlife including nectar-feeding insects and fruit-eating birds as well as deer, raccoons and other wildlife and makes an excellent addition to a coastal landscape. (Pinellas County; B2009-29; Olga Garcia; 18 January 2009.) (Godfrey 1988; Huxley 1992; Nelson 2003; http://www.wildflower.org.)

Persea humilis Nash. (a genus of ca. 200 species in the Asian and American tropics). Lauraceae. Silk bay, scrub bay. The three species of Persea native to Florida are all very similar in general appearance, as well as in many characters of the foliage, flowers and fruits. They differ primarily in habitat preference and in the hairs (pubescence) on their various structures, but most conspicuously on their twigs and the undersides of their leaves. Considered by some taxonomists to be merely a variety of the common red bay, Persea borbonia (L.) Spreng., the silk bay, discussed here, forms a suckering shrub or small tree to 3 m tall with twigs that are densely covered by rusty hairs. The aromatic, leathery evergreen leaves are usually narrowly elliptic to lanceolate in outline and 5-9 cm in length. The undersides of the leaves are reddish brown due to a dense covering of very fine, appressed silky hairs. With proper lighting and magnification, these hairs glisten like short golden threads. As in the other two species, the small greenish flowers are borne in slender-stalked axillary clusters, and they are followed by roundish, black or blue-black drupes. The silk bay is restricted in its distribution to scrub habitats in Central and southern Florida, from Alachua and Putnam Counties south to Martin and Collier Counties. Unfortunately, like all of its close relatives, the silk bay is theoretically susceptible to the laurel wilt disease rapidly being spread by the redbay ambrosia beetle. However, no infected plant of this species has been found. (Submitted by the general public; 9 January 2009.) (Godfrey 1988; Mabberley 1997; Note: redbay ambrosia beetle pest alert available at http://www.freshfromflorida.com/pi/enpp/ento/x.glabratus.html.)

Phoradendron leucarpum (Raf.) Reveal & M.C.Johnst. (a genus of ca. 190 species from the Americas with a concentration in the tropics). Viscaceae (formerly Loranthaceae; recently proposed as Santalaceae). Oak mistletoe. This evergreen subshrub, up to 1 m in diameter, is a hemi-parasite, taking water and nutrients from its host tree, but also carrying out photosynthesis. Heavy infestations of P. leucarpum can reduce the growth of host trees. The leathery, opposite obovate leaves are 2-5 cm long, with entire margins and rounded apices. The flowers are unisexual, with staminate and pistilate flowers on separate plants. These inconspicuous flowers are borne on opposite sides of a jointed spike, with female flowers developing into clusters of ten or more fruits. Each waxy white fruit is 4-6 mm in diameter, with sticky (viscous) flesh, and contains a single seed. Seeds germinate on tree branches, attached there by the sticky fruit pulp. Only one other species in this genus occurs in Florida, P. rubrum, the mahogany mistletoe. It is a rare, parasitic plant found only in far South Florida, distinguished from oak mistletoe by its lemon-yellow to orange fruit. Lore about mistletoe, including the tradition of a kissing under it, began with the European Viscum album, a species similar to the North American mistletoe, but with fewer fruits in each cluster. Both are considered toxic to humans if eaten, although native peoples of eastern North America have used mistletoe extracts medicinally as treatment for a variety of ailments from headaches to whooping cough to ring worms. (Sumter County; B2009-40; Lorrie R. Rigby; 28 January 2009. Palm Beach County; B2009-41; Sallie H. Simmons; 29 January 2009. Volusia County; B2009-42; Albert E. "Bud" Mayfield; 4 February 2009.) (Austin 2004; Godfrey 1988; Mabberley 1997; Wunderlin and Hansen 2003; http://en.wikipedia.org/wiki/Phoradendron; http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7437.html.)

Poinsettia heterophylla (L.) Klotzsch & Garke ex Klotzsch, (a genus of 11 species native to warm parts of the Americas, usually included in Euphorbia). Euphorbiaceae. Mexican fireplant, fiddler's spurge. Like most members of the Euphorbia family, this plant exudes a milky latex if any piece is broken or detached. This latex may cause dermatitis in sensitive people and may have unpleasant effects if ingested. The plant is an annual, pantropical weed closely related, but not very similar in general appearance, to the ubiquitous Christmas decoration, Poinsettia pulcherrima. It grows to about 1 m tall with (usually) unbranched stems. The specific name "heterophylla" meaning "with different leaves" is appropriate since the leaves are extremely variable. They range from ovate and elliptic to narrowly lanceolate in outline; entire, with a few coarse teeth or with shallow lobes along the margin; dull green or gray-green above, often with small, irregularly spaced purple spots; and from 4-15 cm long and 0.5-5 cm broad. As in the florist's poinsettia, modified leaves (bracts) subtend the inflorescence. However, in this species, they are basically colored like the foliage leaves, but occasionally white at the base or with purple spots. The flowers themselves lack petals and sepals and are borne in specialized structures called cyathia, characteristic of Euphorbia and a few closely related genera. According to Dressler (1961), Poinsettia heterophylla is native from Arizona south throughout tropical America and adventive elsewhere. Wunderlin and Hansen (2003) and most other sources consider it to be native also in Florida. It usually grows in disturbed habitats but seldom becomes a pest, although it is currently on Florida's list of noxious weeds (DPI Rule 5B-57.007), under the synonym Euphorbia prunifolia. Its inclusion on the noxious weed list is under review. (Miami-Dade County; B2009-36; Stephen P. Beidler; 27 January 2009.) (Dressler 1961; Wunderlin and Hansen 2003.)

References

Austin, D. F. 2004. Florida Ethnobotany. CRC Press, Boca Raton, Florida. 909 p.

Dehgan, B. 1998. Landscape plants for subtropical climates. University Press of Florida, Gainesville, Florida. 638 p.

Dirr, M.A. 1990. Manual of woody landscape plants, 4th edition. Stipes Publishing Company, Champaign, Illinois. 1,007 p.

Dressler, R.L. 1961. A synopsis of Poinsettia (Euphorbiaceae). Annals of the Missouri Botanical Garden 48: 329-341.

Godfrey, R.K. 1988. Trees, shrubs and woody vines of northern Florida and adjacent Georgia and Alabama. University of Georgia Press, Athens, Georgia. 735 p.

Huxley, A.J. (editor). 1992. The new Royal Horticultural Society dictionary of gardening. 4 volumes. Macmillan Press. London, England. 3,240 p.

Mabberley, D.J. 1997. The plant book, 2nd edition. Cambridge University Press, Cambridge, England. 858 p.

Murphy, T. R. 1996. Weeds of southern turfgrasses. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida. 208 p.

Nelson, G. 2003. Florida's best native landscape plants: 200 readily available species for homeowners and professionals. University Press of Florida, Gainesville, Florida. 411 p.

Wunderlin, R. P. and B. F. Hansen. 2003. Guide to the vascular plants of Florida, 2nd edition. University Press of Florida, Gainesville, Florida. 787 p.