Flora of North America species comparison

Species ca. 15 (1 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera ca. 800, species 22,000–35,000 (701 genera, 208 species in the flora; 1 genus, 6 species introduced).

The overall count for orchid genera in the flora includes Spathoglottis plicata Blume, which was recently reported from Palm Beach County, Florida. The plants, known locally since 1982, are apparently widely naturalized in old shellpits. The number of species in the flora includes one newly recognized species in Habenaria that is morphologically described, but not fully treated here.

Orchidaceae are by far the largest and most diverse monocot family and rank among the largest families of flowering plants. An accurate account of the number of genera and species has eluded orchid scientists, and species counts published in the last 20 years range from 15,000 to 35,000. New species are continually being described. In addition, numerous natural and artificial hybrids exist.

Although orchids are important in horticulture, most of the plants traded in the national and international market belong to a small number of species and their hybrids in only a few genera; the majority of orchids are not commonly cultivated. Few orchids are economically important outside the horticultural trade: the fruits of several species of Vanilla are the source of the spice vanilla, and the dry roots of some species of Dactylorhiza, Eulophia, and Orchis are made into salep, a flour consumed in northern Africa, the Middle East (especially Turkey), and Asia. Some species are locally used for medicinal purposes; the mucilage from pseudobulbs of several species is sometimes used as glue; and in the Far East the stems of some species of Dendrobium are split into strips used to weave handicrafts. A few orchids have been found to cause contact dermatitis (e.g., Cypripedium reginae).

Orchids range vegetatively from Lilliputian plants a few millimeters long (Bulbophyllum Thouars and Platystele Schlechter) to gigantic clusters weighing several hundred kilograms (Grammatophyllum Blume) to some as much as 13.4 meters in height (Sobralia altissima D. E. Bennett & Christenson, a recently described species from Peru). Likewise, flowers vary in size from less than 1 mm and barely visible to the naked eye (Platystele Garay), to 15–20 cm diameter (some Paphiopedilum Pfitzer, Phragmipedium Rolfe, and Cattleya Lindley spp.), and ultimately to 76 cm [Phragmipedium caudatum (Lindley) Rolfe]. Weight can vary from a fraction of a gram (many Pleurothallus R. Brown spp.) to nearly 100 grams (Coryanthes Hooker spp.). Their fragrances vary from delightful (Cattleya Lindley) to repulsive and unbearable (in some species of Bulbophyllum Thouars). The plants colonize habitats ranging from some of the driest and hottest places on earth to the wettest and coolest, literally occurring from polar regions to the equator.

Within the monocots, the most important diagnostic features of Orchidaceae are reduction of adaxial stamens, fusion of the remaining stamens to the gynoecium forming the column, aggregation of pollen into compact pollinia (present elsewhere only in the dicots, in Asclepiadaceae), differentiation of the median petal into the lip, a sometimes complex organ, and the exceedingly small size of the seed, which lacks endosperm. Among other distinguishing characteristics: pollen in the pollinia is usually not available as a nutrient-source (Cleistes Richard ex Lindley being a notable exception), and the often complex interaction with pollinators culminates in the phenomenon of pseudocopulation in several genera (e.g., Ophrys Linnaeus, Caladenia R. Brown sect. Calonema, Drakaea Lindley). In the latter process, the flower mimics the appearance, the smell, and often the movements of a female wasp, attracting a male of a suitable species that tries to copulate with the flower. It usually only succeeds in becoming attached to a pollinium, which will then be transferred if the male tries to copulate with another flower.

Roots of orchids may be covered with velamen, spongy layers derived from the epidermis; fleshy thickenings of roots are tuberoids (tubers being restricted to stems). Stems may be swollen or thickened, underground corms or aerial pseudobulbs. Flowers are often resupinate: the lip (modified median petal) is “lowermost,” usually as a result of the pedicel being twisted or bent in its development by 180°. Pedicellate ovary, usually used in reference to length, refers to the combined pedicel and ovary. Flowers are not always borne on pedicels; when they are, it is sometimes difficult to distinguish between a slender ovary and the pedicel. Consequently, because of their slender ovaries, flowers of a “racemose spike” appear to be pedicellate even though they are sessile, while a “spicate raceme” has pedicels so short that they appear to be absent. Orchid flowers often have a modified median sepal, the dorsal sepal. Sepals coalescing at their tips form a synsepal. The middle portion of the upper (adaxial) face of the lip is the disc: it may be a thickened callus and may bear hairs, papillae, or other ornamentation. In orchids the style, stigmas, filaments, and one or more anthers are united to form a column; appendages projecting laterally from the stigma are column wings; the lip may be attached to the protrusion at the base of the column to form a column foot; lateral sepals that are also attached to the foot form a mentum (chin). In most orchids the column bears a single anther at its apex; the clinandrium is the cavity within which the anther is borne or embedded. Pollen is borne in discrete masses (pollinia). Genera with mealy (sectile) pollinia may have pollinia within the anther tapering into a caudicle (stalk), which is attached to a sticky viscidium. Those with waxy pollinia have pollinia attached to one or two stipes (of stigmatic origin and formed outside the anther), which in turn are attached to a viscidium. The various aggregations of pollinia, caudicles, stipes, and viscidium form a pollinarium, the pollination unit carried by pollinators. The median stigma lobe may have a slender extension or little beak (rostellum), which aids in gluing the pollinarium to the pollinator.

Taxa excluded from the flora as neither native nor definitely naturalized are discussed below.

Bletia florida (Salisbury) R. Brown, grows in gardens near Homestead, Florida. This species has escaped and may persist but does not spread to the surrounding area (P. M. Brown 2002).

Bletia patula Hooker is an apparent garden escape (P. M. Brown 2000). A single vegetative specimen, which later flowered, was collected in 1947. No specimens that can be referred to this species have been collected or seen since then (P. M. Brown 2002).

Bletilla striata (Thunberg) Reichenbach f. is a garden escape (P. M. Brown 2000, 2002) that has been reported growing along roadsides and in lawns in Escambia County, Florida (G. S. Wilhelm 1984). A specimen is located in FLAS but its naturalized status cannot be established (R. Wunderlin, pers. comm.).

Brassavola nodosa (Linnaeus) Lindley is a dubious record (C. McCartney 1997; P. M. Brown 2000, 2002).

Encyclia rufa (Lindley) Britton & Millspaugh has been excluded because only one specimen has been recorded. R. P. Sauleda and R. M. Adams (1983) considered it to have been introduced.

Epidendrum blancheanum Urban is endemic to Hispaniola. It is not confirmed for Florida.

Epidendrum radicans Pavón ex Lindley has been reported to be a persistent escape in Lee County, Florida (P. M. Brown 2000). Two specimens previously identified as this species from Captiva Island, Florida, are probably hybrids and not the pure species, which is very easily identified (E. Hágsater, pers. comm.).

Gymnadenia conopsea (Linnaeus) R. Brown was reported for Litchfield, Connecticut, by R. C. Bean et al. (1951), who noted that a specimen was in the herbarium of the Torrey Botanical Club but that the station has not been relocated. Apparently the species did not persist (P. M. Brown 1997), and it is not a likely naturalization.

Laelia rubescens Lindley was discovered in 1999, growing on a large branch of a live oak in Hammock County Park, Miami, Miami-Dade County, Florida. It was believed to have originated from seed rather than an intentional planting because the plant could be traced from a pea-sized pseudobulb for at least 8 growth periods, and other seedlings were found in the area (P. M. Brown 2000, 2002). The species may be a possible naturalization.

Leochilus labiatus (Swartz) Kuntze was reported by C. A. Luer (1972) to be naturalized in Florida based on second-hand evidence (C. McCartney 1997). The purported occurrence in the Fakahatchee Swamp may have been a deliberate deception at Luer’s expense (R. L. Hammer, pers. comm.). All of Luer’s photographs were of cultivated plants and there is no herbarium voucher. Its reported naturalization in Florida is dubious (P. M. Brown 2000).

Lophiaris carthagenensis (Jacquin) Braem was reported in Florida [as Oncidium carthagenense (Jacquin) Swartz] based upon a single specimen collected by J. K. Small in 1916, at Coot Bay (near Flamingo in Everglades National Park), Monroe County, Florida (D. S. Correll 1950; C. A. Luer 1972). The specimen, in New York, includes a partial inflorescence and lacks foliage. A number of attempts were made to relocate the species at Coot Bay but all were unsuccessful (R. P. Sauleda and R. M. Adams 1989; R. L. Hammer, pers. comm.). Sauleda and Adams suggested that the specimen collected by Small had come from a garden in southern Florida where he kept plants until they flowered. They stated that Small probably collected the specimen under the mistaken belief that the plant was collected in Florida although it had actually come from Central America. Others, including P. M. Brown (2000), simply consider it to be a possible introduction but not naturalized.

Maxillaria sanguinea Rolfe has reportedly become naturalized, but naturalization of the species in the flora area is dubious (C. McCartney 1997; P. M. Brown 2000).

Restrepiella ophiocephala (Lindley) Garay & Dunsterville was reported to occur in North America. Apparently, it has not become naturalized in the flora area (P. M. Catling, pers. comm.). It is considered a dubious record (C. McCartney 1997; P. M. Brown 2000).

Tetramicra canaliculata (Aublet) Urban was treated as naturalized in the flora of Florida (C. A. Luer 1972). Recent evidence (C. A. Luer, pers. comm.) indicates that the species is not native and has not become naturalized. Moreover, it has not been reported for Jamaica or Cuba and reports for the Bahamas are erroneous (D. S. Correll and H. B. Correll 1982). Other citations (L. A. Garay and H. R. Sweet 1974; J. G. Williams and A. E. Williams 1983) also are erroneous, probably based on C. A. Luer (1972). The scenarios that could have led to this and other cases of dubious reports of naturalized orchids are discussed in C. McCartney (1997).

(Discussion copyrighted by Flora of North America; reprinted with permission.)