Florida bears a permanent geologic link to Africa because the lowest strata of rocks underlying the peninsula are a piece of the African continent. As discussed in Part I of this article (Orchids, February 2000), these rocks are a remnant of the time some 210 million years ago when the supercontinent Pangaea split apart and the continents as we know them began to drift toward their current positions on the globe.
Part I concentrated on some of the more recent biological connections between Florida and Africa, discussing the four orchid species they share directly: Polystachya concreta, Liparis nervosa, Eulophia alta and Oeceoclades maculata.
Parts II and III will look at a few Florida species with close relatives in Africa, as well as some orchid genera shared between these two areas of the world now so distantly divided.
Besides the four orchid species Florida shares directly with Africa, four other species could be classified as close relatives:
Although this plant was treated as Eulophia ecristata in Carlyle A. Luer's monumental The Native Orchids of Florida (1972), it is now placed in the genus Pteroglossaspis (although for how much longer remains uncertain). It is related to both Eulophia alta and Oeceoclades maculata discussed at the end of Part I.
H.G. Reichenbach the younger's genus Pteroglossaspis – pronounced tair-ohgloss-SASS-pis and coming from three Greek words for “wing,” “tongue” and “shield,” referring to the paired column wings (Mayr, 1998) – is a segregate from Eulophia and, like that genus, it is Africa-centered. It includes three to seven species, depending on the authority consulted.
According to Jeffrey Wood of Britain's Royal Botanic Gardens, Kew, five species are found in tropical and subtropical Africa (personal communication). Besides Pteroglossaspis ecristata, one other species occurs in the New World, a species of Argentina and Brazil once called Pteroglossaspis argentina and now considered synonymous with the African Pteroglossaspis ruwenzoriensis.
Wood writes, “Pteroglossaspis is closely allied to Eulophia, particularly to the African E. albo-brunnea Kraenzl. and E. shupangae (Rchb.f.) Kraenzl. and allied species, which are virtually identical in habit. The genus differs, however, in having a flat, unspurred labellum and by the usually very short, biauriculate column. Future molecular studies, however, may show Pteroglossaspis to be nested within Eulophia.”
Pteroglossaspis ecristata is not a particularly tropical orchid. In fact, the type specimen of 1897 was from northeastern Florida, and the species is much more common north of Lake Okeechobee than it is at the southern end of Florida. It is also found in southern Louisiana and coastal regions of South and North Carolina, with an anomalous report from the mountains of North Carolina. In Subtropical South Florida, it is reported only from Collier and Dade counties. Many of the Dade County populations appear to produce only cleistogamous (closed) flowers or those that are nearly so. The species also is reported for Cuba, and has been, discovered as far away as Colombia (Romero, 1993).
This is primarily an orchid of sandy pinewoods and dry, fallow fields. Even in the pine rocklands of southern Dade County, the plant seems to occur only in pockets of sand within the oolitic limestone substrate.
This orchid looks much like a Eulophia, producing long, yellowishgreen basal leaves and a tall inflorescence with the flowers at the tip. These flowers are yellowish green with maroon markings on the lip. All the other floral segments converge over the entrance to the lip. The flowers are produced in July, August and September in Florida.
The state classifies Pteroglossaspis ecristata as threatened (Coile, 1998), although it could be argued that it should be upgraded to endangered status because of Florida's exploding human population and the resulting developmental demands for this orchid's dry upland habitats.
The Leafless Orchids
Among the most interesting of South Florida's native tropical orchids are its three leafless species. These are all related to the African angraecoid orchids in the subtribe Angraecinae, as Robert L. Dressler points out in Phylogeny and Classification of The Orchid Family (1993), subtribe Angraecinae, and are among a handful of outliers from that group whose ancestors somehow made it across the Atlantic in some past geologic epoch.
The evolution to a leafless state is a fascinating adaptation. Interestingly, though, all three Florida species have leaves or a leaflike structure at the seedling stage. But once the plant is established and the proper mycorrhizal fungus association is achieved, that seedling leaf drops off and the plant remains leafless throughout the rest of its life. As an adult, the plant is little more than a group of roots growing from a short central stem, like the spokes radiating from the hub of an old-fashioned wagon wheel.
The roots of two species, Polyradicion lindenii and Harrisella porrecta, appear to contain chlorophyll because they are a gray-green color with green growing tips. This is a little more difficult to see in the third species, Campylocentrum pachyrrhizum, which has roots with bronze-colored growing tips.
It seems clear that these orchids must depend on their mycorrhizal associations throughout their lives because the amount of chlorophyll in the roots hardly seems sufficient to provide all the necessary nutrients for the plant. This could account for these species' being notoriously difficult to keep alive under cultivation, although a few people have been successful at doing so. The fungal associations of these leafless orchids is ripe for scientific inquiry.
Moisture and protection from cold are two other serious considerations for orchids in a leafless state. Two of the species in Florida, Polyradicion lindenii and Campylocentrum pachyrrhizum, solve this problem by growing primarily in swamps on tree trunks below the leafy canopy, which traps both moisture and heat beneath it. The third species, Harrisella porrecta, grows in much sunnier, open habitats (including abandoned citrus groves). Its reduced size may help it adapt to this brighter, potentially drier environment. Also, the fact that it is a shortlived, small-twig epiphyte may contribute to its inclination to colonize such seemingly risky habitats.
The state of Florida rightly classifies Polyradicion lindenii and Campylocentrum pachyrrhizum as endangered (Coile, 1998). Harrisella porrecta, on the other hand, is so plentiful in the state that it may not deserve its status as threatened.
Here is a brief look at Florida's leafless orchids:
(Reichenbach f.) Rolfe
There are about 55 species of the New World genus Campylocentrum (Dressler, 1993). Some of these, like this Florida representative of the genus, are leafless. Others, like the widespread Campylocentrum micranthum, are leafy monopodial orchids looking very much like their African ancestors – and appearing to be out of place in the American tropics.
Of Florida's three leafless orchids, C. pachyrrhizum is the most restricted in its range in the state. It is found primarily in the deep swamps of the Fakahatchee Strand of southwestern Florida and in a few surrounding areas of the adjacent Big Cypress Swamp. It is encountered fairly frequently in the Fakahatchee, usually on the vertical trunks of swamp trees at not much higher than eye level. It even grows on the mossy trunks of the native royal palms (Roystonea regia, formerly R. elata) that grow naturally in that area.
The aforementioned bronzy tip is a good characteristic to identify it when not in flower. Another way is the shape of the roots themselves. They tend to be flat compared with the other two leafless species in Florida, and the edges are even thinner, with wavy margins. Because of the flatess of these roots – the species name means “thick root,” although “wide root” might be more appropriate – the common name ribbon orchid has been coined for this species. It is a wonderfully descriptive name which, unfortunately, hasn't caught on yet. The species sometimes is called the crooked-spur orchid, but that name could apply to almost any member of the genus because that's what Campylocentrum means.
The dense, brushlike clusters of C. pachyrrhizum's tiny white flowers are borne in the autumn in Florida. Each bloom bears a clublike spur, which is large relative to the size of the flower. After the flowers are pollinated, they develop into short clusters of seed capsules that remind some of a bunch of fat green bananas.
(Reichenbach t.) Fawcett and Rendle
This is the smallest of Florida's three leafless orchids.
It is great fun in the field to introduce people to this tiny orchid, which is, in terms of plant mass and flower size, the smallest of the state's 100-plus native orchids. The neophytes are stopped in front of a likely cypress sapling, usually one with mosses and lichens growing on its branches, and are told to find the orchid. They search and search before they give up. Then they are pointed to the few tiny gray-green roots of the Harrisella. The response most often is: “How did you see that?”
If it's autumn and the plants are in bloom, the task of finding them is easier. And it's easier still when the round seed capsule has formed because it is the biggest single structure of the plant. The round shape of the little capsule accounts for this species' cute common name of jingle bell orchid. After the capsule matures, it turns orange and opens wide at the end, dehiscing its minute seeds. The old seed capsules look almost like little flowers themselves.
Besides cypress trees (Taxodium species), H. porrecta grows on a number of other hosts, including such diverse species as laurel oak (Quercus laurifolia) , hog plum (Ximenia americana) , buttonwood (Conocarpus erectus) , the nonnative guava (Psidium guajava) , and even the older woody stems of the climbing swamp aster (Aster carolinianus).
Some recent texts (Wunderlin, 1998, for example) use the name Harrisella filiformis (Swartz) Cogniaux for this species. But James D. Ackerman of the University of Puerto Rico cautions against this. In An Orchid Flora of Puerto Rico and the Virgin Islands (1995), he notes: “Harrisella porrecta is sometimes confused with H. filiformis ..., but a comparison of the types ... clearly shows that they are distinct.” In fact, Ackerman considers Harrisella filiformis to be a species of Campylocentrum.
Even though Dressler (1993) lists the genus Harrisella as having three species, Ackerman treats it as monotypic, with H. porrecta as its sole species. All other names associated with Harrisella he considers to be synonymous with Harrisella porrecta or to be members of the genus Campylocentrum. And Dressler (1993) notes that the genus Harrisella is “similar to or the same as” Campylocentrum.
Polyradicion lindenii (Lindley) Garay
There is no mistaking this orchid for either a Harrisella or a Campylocentrum when it is in flower. This is Florida's legendary ghost orchid, made even more famous by the recent book The Orchid Thief.
A spider's web of thick, gray-green roots with bright green tips radiates out from a central hub on the trunks of cypress, pond apple (Annona glabra) or popash (Fraxinus caroliniana) trees on which this orchid grows, accounting for the orchid's generic name, which means “many roots.” The earlier generic name by which this orchid has long been known, Polyrrhiza, means exactly the same thing. The ghost orchid even grows on the mossy vertical trunks of native royal palms in the Fakahatchee Strand, accounting for another of its less familiar but still fanciful common names, palm-polly.
This is one of Florida's largest-flowered native orchids, which is all the more surprising considering the minimal plant material from which it grows.
In late spring or early summer, a wiry little inflorescence emerges from the plant's short central stem at the nexus of the roots. It elongates to several inches then produces a green bud that swells into a white flower some two-plus inches across and even longer top to bottom. The sepals and petals may be greenish-white, and the petals fold backward as the flower matures. But the large lip is pure white. Its big mid lobe has two long, slightly twisting appendages hanging from either side, causing some imaginative folk to say the flower resembles an albino frog leaping through the air. The scooplike lip is drawn into a long spur that dangles some three to four inches from the back of the flower.
When in bloom, it is easy to see that this orchid is a relative of the African angraecoids.
Because the ghost orchid is glowing white and night-fragrant, it is assumed to be pollinated by one of Florida's giant nocturnal sphinx moths, and that well could be the primary pollinator. But in June of 1999, a flower was observed being visited in the daytime by a giant swallowtail butterfly (Papilio cresphontes). The butterfly appeared to be stuck in the flower, but when it was gently extricated, it emerged with the orchid's pollinarium adhering to its head, raising the possibility that this might be a secondary pollinator for this unique orchid.
The deep, shady pond apple and popash swamp where this observation was made is typical of the orchid's habitat, and it is home to numerous healthy ghost orchids. Seed capsules are encountered there with some regularity. These capsules are long, thin, narrowly terete and curved scimitarlike. They develop quickly over a matter of a month or so after pollination, then remain approximately the same size for nearly a year, until they mature and dehisce their seeds. It is clear that this particular swamp is a happy environment for this orchid.
Although the ghost orchid has been made famous because of its association with the Fakahatchee Strand, the orchid is found in suitable pond apple swamps throughout the Big Cypress. Wading waist-deep into the cool, clear tannin-stained water of these swamps on a hot summer day to see this orchid is an experience to be cherished.
Luer (1972) showed the distribution of what he treated as Polyrrhiza lindenii to be South Florida (where it is mostly localized in Collier County), Cuba and the Bahamas. However, the massive Flora of the Bahama Archipelago (Correll and Correll, 1982) does not list this species for the Bahamas or the adjacent Turks and Caicos Islands.
As the species is now understood, its distribution also includes the island of Hispaniola, which is divided between Haiti and the Dominican Republic. It is shown in a large, full-color photograph on the cover of the March 1984 issue of the Boletin de la Sociedad Dominicana de Orquideologia, and the article in that issue by Adolph Gottschalk discusses the fact that the Hispaniolan orchid once was known as Polyradicion sallei. But now, he says, that species is considered to be synonymous with Polyradicion lindenii. The only noticeable difference between the Florida flowers and those from the Dominican Republic illustrated in Gottschalk's article is that the spur on those flowers points upward, whereas it curves distinctly downward in the flowers of Florida plants.
Dressler (1993) lists four species for the genus Polyradicion, but he indicates that he considers the genus “very similar to” Dendrophylax, another Caribbean genus of leafless angraecoid orchids, calling the separation of the genera into doubt.
Next month, Part III will explore five other genera Florida shares with Africa.
Ackerman, James D. 1995. An Orchid Flora of Puerto Rico and the Virgin Islands (Memoirs of The New York Botanical Garden, Vol. 73). The New York Botanical Garden, Bronx.
Coile, Nancy C. 1998. Notes on Florida' s Endangered and Threatened Plants. Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Bureau of Entomology, Nematology and Plant Pathology – Botany Section, Contribution No. 38, 2nd edition, Gainesville.
Correll, Donovan Stewart, and Helen B. Correll. 1982. Flora of the Bahama Archipelago. J. Cramer, Vaduz.
Dressler, Robert L. 1993. Phylogeny and Classification of the Orchid Family. Dioscorides Press, Portland.
Gottschalk, Adolph. 1984. Polyradicion lindenii: The Little Toad Orchid, Boletin de la Sociedad Dominicana de Orquideologia, 2(2):16-21.
Luer, Carlyle A. 1972. The Native Orchids of Florida. The New York Botanical Garden, Bronx.
Mayr, Hubert. 1998. Orchid Names and Their Meanings. A.R.G. Gantner Verlag K.-G., Vaduz.
Romero, Gustavo A. 1993. Notes on Pteroglossaspis (Orchidaceae), a new generic record for the flora of Colombia. Orquidea (Mex.) 13(12):275-280.
Wunderlin, Richard P. 1998. Guide to the Vascular Plants of Florida. University Press of Florida, Gainesville.
Chuck McCartney, a former assistant editor (1984 to 1988) and editor (1988 to 1989) of AOS Bulletin, is an avid student of Florida' s native orchid flora. He currently works for The Miami Herald – 2546 Scott St., Hollywood, FL 33020-2357.