Ephedra distachya [Otto Wilhelm Thomé] (Stüber 1999).
Distribution of Ephedra (Caveney et. al. 2001).
Ephedra distachya [Otto Wilhelm Thomé] (Stüber 1999).
Distribution of Ephedra (Caveney et. al. 2001).
Ephedra
Mormon-tea, joint-fir, cañatilla, popotillo, tepopote (Stevenson 1993), 麻黄属 ma huang shu [Chinese] (Fu et al. 1999).
Ephedra is the sole genus in Ephedraceae Dumortier 1829, which some authors designate as the sole family in Order Ephedrales Dumortier 1829 (alternatively, in Order Gnetales Luersson). Its position among the gnetophytes is almost universally accepted, where it is part of a monophyletic clade sister to the genera Gnetum and Welwitschia (Ickert-Bond and Renner 2016). Phylogenetics in the genus are highly correlated with geography, with distinct groups in the Americas, Asia, and the Europe-Mediterreanean region (Huang et al. 2005, Rydin and Korall 2009).
Ickert-Bond and Renner (2016) summarize phylogenetic relationships within Ephedra as follows: "Molecular phylogenies of Ephedra by now have included 56 species. In combination, they show that the six Mediterranean species form a grade at the base of the phylogeny, while the remaining 50 species from a well-supported clade. All 22 New World species form a clade that is nested within a paraphyletic Old World grade. Within the New World clade, the North American E. pedunculata is the earliest diverging species and sister to two clades, one with ten South American species and one with eleven North American ones." They note that a molecular clock study indicates divergence of the Old and New World taxa in the Oligocene.
The family has been around at least since the early Cretaceous, at which time it contained at least one genus (Ephedrispermum) in addition to Ephedra (Rydin et al. 2006). The surviving species seem to be a relict group that happens to have done well during the climate changes, principally the development of very extensive semiarid habitats, that have swept the globe since the Oligocene.
Unlike other gymnosperms, the chloroplast genome in Ephedra is inherited maternally (Mogensen, 1996); as a result chloroplast data relate gene spread via seed dispersal, rather than pollen dispersal.
With 51 species evaluated, polyploidy has been detected in over three-quarters of Ephedra species. This is the highest incidence of polyploidy observed in gymnosperms. There are 13 diploid and 24 polyploid taxa (4X to 8X), with 18 taxa showing intraspecific incidence of polyploidy. The polyploids have variously arisen through both interspecific hybridization and autopolyploidy, and the frequency of asexual reproduction (through rhizomes) has been cited as a factor influencing the relative abundance of polyploidy in the genus (Ohri 2021).
Plants of the World Online regards the following 71 species as valid. This is probably an excessive number; it includes a substantial number of recently-described species that may eventually reduced to synonymy with existing taxa; Ickert-Bond and Renner (2016), for instance, recognize 54 species, about equally divided between Old World and New World taxa. Those authors particularly suggest that recently-described species from India and China "appear morphologically close to E. intermedia and E. saxatilis," and that "diagnoses rely heavily on straight vs. coiled micropyles, a character of limited significance." The underlined links shown below are taxa of doubtful validity. Besides these, there are 3 described nothospecies, all quite rare:
List of taxa:
Perennial, dioecious (rarely monoecious), erect, procumbent or climbing shrubs or vines. Bark grey to reddish brown, cracked and fissured, often fibrous. Branching is often broom-like with nearly parallel and fastigiate to ascending green stems. Branches photosynthetic, yellowish green to olive-green when young, round, finely longitudinally grooved, jointed, internodes 1-10 cm. Roots generally fibrous. Leaves mostly not photosynthetic; opposite or in whorls of 3; simple, scalelike, connate at base to form a sheath, generally ephemeral; resin canals absent. Cotyledons 2. Pollen cones 1-10 in whorls at nodes, each compound cone composed of 2-8 sets of opposite or whorled membranous bracts, proximal bracts empty, distal bracts each subtending a small cone composed of 2 basally fused bracteoles subtending a sporangiophore bearing 2-10(-15) sessile to long-stalked, bilocular, apically dehiscent, pollen-producing microsporangia. Pollen ellipsoidal, with 6-12 longitudinal furrows, not winged, average diameter 27–58 µm. Seed cones 1-10 in whorls at nodes of twigs, each compound cone sessile or on short to long peduncle, composed of 2-10 sets of overlapping, opposite or whorled, membranous or papery to fleshy bracts, proximal bracts empty, most distal bracts subtending 1 axillary cone composed of a pair of fused bracteoles enclosing a single-integumented ovule with integument projecting as tube from bracteole-envelope, envelope forming a leathery "seed coat" that is shed with seed. Seeds 1-2(-3) per compound seed cone, yellow to dark brown, smooth or furrowed. Wood ring porous, lacking resin ducts, with wide multiseriate rays and vessels in older stems; vessels most abundant and largest in lianoid species, whilst nearly lacking in alpine species (Stevenson 1993, Fu et al. 1999, Ickert-Bond and Renner 2016).
Ephedra has three types of female cones. These were formerly used by Stapf (1889) to define Sections in the genus, although later molecular analyses have ended use of that nomenclature. Nonetheless, the cones are a very useful identification feature. The first type (Sect. Alatae) bears free, dry, winged, membranous bracts. Second, Sect. Asarca has free, dry, but coriaceous bracts. Third, Sect. Ephedra has thickened, colorful, and fleshy bracts. Sections Alatae and Asarca are nested within Sect. Ephedra, suggesting that the fleshy cone is basal in Ephedra.
Ephedra is immediately distinctive in appearance due to its diminutive, often nonphotosynthetic leaves and its ribbed round green stems, which are photosynthetic. In cross-section the stems reveal stomata and intercellular spaces, and otherwise resemble leaf anatomy in certain ways. The wood contains abundant vessels and resin canals are absent. Leaves appear in pairs or whorls of 3 at the stem nodes, fused at the base into a sheath, and are often early-deciduous. The reproductive structures anatomically resemble conifer cones, in that they consist of a number of bracts whorled or decussate around a central axis, with pollen exposed in the pollen cones and ovules open to the air in seed cones. These structures are also often called male and female strobili, which are general terms that can be applied to the reproductive structures of all gymnosperms (except female Ginkgo plants). Ephedra is dioecious and there have been a number of errors in which type specimen collections included a male of one species and a female of another (e.g., E. aphylla). The pollen cones are ovoid and appear solitary or clustered (up to 12) at the nodes. Each cone has a central axis around which are pairs of 2 to 12 bracts. When the cone is fertile, yellow sporangiophores, analogous to the stamens of flowering plants, each with 2-3 terminal lobes called "locules", protrude from between the bracts and bear pollen. Most Ephedra species are wind-pollinated, but two species basal to the Ephedra clade (E. aphylla and E. foeminea) are insect pollinated (by flies and/or moths), and the other two families of the Gnetales are exclusively insect-pollinated, indicating that wind pollination developed independently in Ephedra (Rydin and Bolinder 2015). The female cones are also structures of paired bracts formed at nodes, but consist of only 2-4 paired bracts, with two opposite cones in decussate arrangement at the node; when fertile, they are smaller than the pollen cones. One pair of bracts is fertile, containing ovules open to the environment (hence, a "gymnosperm") via a micropylar tube. If fertilized, typically only one ovule develops a seed. In some species, the seed is contained within a fleshy integument, often bright red or orange, that is simply the mature ovary; I call it a "fruit" because it looks like one, though technically it is the female cone. Seeds are dispersed by wind, birds, or rodents, with different dispersal mechanisms predominating in different species.
For proper identification of Ephedra, fruiting and flowering material is essential. Many sterile specimens of various taxa look alike (Ali and Qaiser 1987), though some vegetative characters are quite useful, particularly the length of sheath of leaves attached at nodes.
Deserts, semideserts, desert steppes, or seasonally dry habitats such as mediterranean-type evergreen or deciduous woodlands and subtropical thorn scrub; in both the Old and New Worlds. Often forms clonal colonies (Ickert-Bond and Renner 2016).
The various species are distributed as follows (note that species numbers are approximate):
Their habitats are all described as dry, rocky and/or sandy. A few species occur in grasslands, and for a few species, habitat is not specified.
One species occurs in Argentina and Chile, from Tierra del Fuego to 42° S.
Two species occur in North Africa, one of which also occurs in SW Asia (Saudi Arabia, Kuwait, Israel) and Cyprus.
Twelve species are in the USA (Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Wyoming) of which 5 species also occur in Mexico (Baja California Norte, Chihuahua, Coahuila, Nuevo León, San Luis Potosí, Sonora).
The remaining 21 species are Eurasian, with focal areas in central Asia (18 species) and around the Mediterreanean (4 species, plus the North African ones). These break out according to country as follows:
The New World species occur at elevations ranging from below sea level in Death Valley to about 5000 m for E. rupestris in the Andes of Ecuador. The Old World species are found from sea level to 5300 m elevation (E. gerardiana, the highest elevation occupied by any gymnosperm species). E. intermedia probably has the greatest elevational range of any single gymnosperm species, ranging from 100 to 4600 m elevation across its vast range.
The Ephedraceae are the only widespread group of gymnosperms that are not of conservation concern. The IUCN (2020) has not identified any taxa as critically endangered, endangered, or vulnerable, and only one is listed as "near threatened." This happy situation is probably due to the fact that Ephedra generally occupies arid and semiarid habitats that are poorly suited for agriculture or development, is unpalatable to livestock, and has large areas of occurrence.
Seed dispersal varies between species; some are dispersed by wind, some by small mammals who cache the seeds, and some (primarily ones with colorful fleshy seed cones) by birds, which eat the cones and defecate the seeds (Hollander and Vander Wall 2009).
E. boelckei is one of the few species that can grow as a tree, reportedly up to 4.5 m tall.
I have found no records of specimen age. I once cut the stem of a large dead specimen, likely E. viridis, and found that it appears to form annual rings; there were 43 of them.
Throughout its distribution it is used by native cultures for a variety of medicinal purposes, including cough medicines, an antipyretic, an antisyphilitic, a stimulant for poor circulation, and an antihistamine. These uses are based on the presence of tannins and alkaloids, particularly ephedrines (Stevenson 1993). In recent times, it has achieved widespread popularity as an 'herbal medicine' used in weight-loss preparations and 'energy' preparations (both uses due to its stimulant effects) and cold and allergy medications (due to the presence of the bronchodilator ephedrine) (Herbal Information Center. [no date]).
The old world species contain variable amounts of ephedrine; curiously it is not present in the New World species, and the psychotropic properties ascribed to "Mormon Tea" and its relatives remain unknown. The oldest drug produced from Ephedra is the Chinese ma-huang, which has been used in Chinese medicine for over 5000 years to treat fever, nasal congestion and asthma. Ma-huang is widely sold in the western world, usually with dubious claims as to its curative values (literature review by Caveney et al. 2001). Ephedra has also been used in the synthesis of methamphetamine (Andrews 1995).
Ephedra is not used in dendrochronology, but there is likely some potential, since it produces growth rings, which in most cases are of roughly annual frequency.
See the species accounts.
Named from the "Greek ep-, upon, and hédra, seat or sitting upon a place; from the ancient name used by Pliny for Equisetum; the stems resemble the jointed stems of Equisetum, the segments of which appear to sit one upon the other" (Stevenson 1993).
"In Ephedra the habit varies greatly even in the same species. Dwarf bushes a few inches high are common (E. distachya, etc.). E. distachya and other species are also represented by tall bushes up to 6 ft. in height, with virgate branches. E. triandra may attain the habit of a small tree with a trunk a foot in diameter. Climbers of the "weaver" type with slender pendent branches are found in E. altissima and E. fragilis: these and other species include forms in which the branches are prostrate.
"Most species, especially in loose soils, spread by means of branching rhizomes which arise from buried nodes of the erect stems; they thus exert a binding effect upon the soils in which they grow. In E. alata, growing in the sand dunes of the Areg formation of Algeria and Tunis, the rhizomes attain a length of several metres and form efficient sand binders. Erect shoots of the normal type arise from the axils of the younger leaf-sheaths. When these shoots are isolated by the breaking or decay of the parent rhizome they differ from seedlings only in the absence of tap-roots" (Pearson 1929).
Ali, S.I. and M. Qaiser (eds.). 1987. Flora of Pakistan. http://www.efloras.org.
Andrews K.M. 1995. Ephedra's role as the precursor in the clandestine manufacture of methamphetamine. Journal of Forensic Science 40: 551-560.
Caveney, Stanley, David A. Charlet, Helmut Freitag, Maria Maier-Stolte and Alvin N. Starratt. 2001. New observations on the secondary chemistry of world Ephedra (Ephedraceae). American Journal of Botany 88:1199-1208. http://www.amjbot.org/cgi/content/full/88/7/1199, accessed 2006.10.18.
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