Pedilanthus cymbiferus inflorescences   The Pedilanthus Page

Pedilanthus is a clade within the very large genus Euphorbia (Euphorbiaceae). It is distinctive not only because of its inflorescences, which in various species resemble everything from shoes to ducks, but also because of the great range of life forms and habitats that the 15 or so species occupy. Most, such as the relatively well-known "Devil's backbone" P. tithymaloides, are small leafy shrubs that grow in tropical dry forests of Mexico and the Caribbean. Other species, such as P. calcaratus , may become small woody trees of tropical dry forests. Species such as P. cymbiferus (shown at right) and P. macrocarpus are leafless or nearly-leafless stem succulents with water storage tissue in the pith and bark. One species, P. finkii, grows in moist tropical forests of central Mexico. Click on the thumbnails below for a larger image. Visit the publications page to see a report on the conservation status of the species of the clade in Mexico.

Pedilanthus macrocarpus

Pedilanthus macrocarpus cristate This species is a leafless stem succulent from the Sonoran Desert of northwestern Mexico. This photograph is from the central Baja California Peninsula. One of the stems in this photos is cristate, that is, the meristem has become a long and convoluted line rather than a tiny globular cluster of cells.
Pedilanthus coalcomanensis
P. coalcomanensis habit This species was discovered in a remote mountain range in western Mexico in the 1930s. Unfortunately, the information on the herbarium specimen label was so vague that its exact location was unknown. We recently located a population of this species, which forms graceful small trees with large, colorful inflorescences, fuzzy leaves and tuberous roots. This photo was taken in the winter dry season.

These images were taken in the summer rainy season to show that this species grows in one of the most strikingly seasonal tropical dry forests we've ever visited. This area resembles a cloud forest in the rainy season, but is baked dry for half of the year. Here, Pedilanthus coalcomanensis forms a dense, shady stand.

The fuzzy leaves of Pedilanthus coalcomanensis

In keeping with the very wet wet seasons of the area, the trunks of Pedilanthus coalcomanensis are covered with dense mats of lichens, mosses, and epiphytes.
inflorescences of Euphorbia (Pedilanthus) coalcomanensis
The inflorescences of Euphorbia (Pedilanthus) coalcomanensis are spectacular. The bright green cyathia project from brilliant pink bracts when the plant, as well as most of the surrounding forest, is leafless and gray.
inflorescence of Euphorbia (Pedilanthus) coalcomanensis This image shows the male and female flowers projecting out of the green cyathia of Euphorbia (Pedilanthus) coalcomanensis. Like so many plants, we do not know what polliates the flowers of this microendemic species.
Pedilanthus calcaratus
Pedilanthuss calcaratus inflorescence
Pedilanthus calcaratus is the most widespread of the woody treelets in the genus. Plants are often 2-3 meters tall with large, evergreen leaves in the southern part of the range, as in the photos below. Farther north, such as where the specimen at left was photographed in Michoacán, the plants lose most of their leaves in the dry season.

Pedilanthus nodiflorus
Pedilanthus nodiflorus inflorescences
The exposed glands on either side of each inflorescence become covered with fungi with age, darkening them and emphasizing the appearance of a cow's skull. 
Pedilanthus nodiflorus in Yucatán
In Mexico's Yucatán Peninsula, this species is found in clearings in dense deciduous forest just inland from mangrove swamps. The small tree at left is a Cnidoscolus, another member of Euphorbiaceae.
Pedilanthus finkii
Pedilanths finkii in the forest
The incredible range of life form and ecological tolerance of Pedilanthus reaches an extreme in P. finkii. This species grows in tall, wet tropical forest, where its leaves are covered with lichens and mosses. It grows as a shrub with stems that root in the moist leaf litter when they fall over. The plants in the population shown here grow in cracks and hollows in limestone in Oaxaca. 
Pedilanthus tithymaloides
Pedilanthus in the woods
Pedilanthus tithymaloides has the widest range of all of the species, ranging from South America to Tamaulipas, Mexico, and the Caribbean. It varies somewhat in habit. In Mexico, it is most often a small shrub, such as the three individuals shown in the foreground in this image from southern Oaxaca where it grows in the understory of dense tropical dry forest. 
Pedilanthus diazlunanus
Pedilanthus diazlunanus
One of the stem succulent members of the genus, this species is found only in a small part of southern Jalisco where it grows in rich and highly scenic tropical dry forest.

The inflorescence of P. diazlunanus is unusually short relative to its length. Unlike most species of Pedilanthus, it is probably pollinated by insects rather than hummingbirds.
Pedilanthus pulchellus
Pedilanthus pulchellus inflorescence
This beautiful species with a bright red-orange inflorescence was known only from a single collection from a mountain in Oaxaca in 1917, but there was some confusion as to where exactly it occurred. It had not been seen again until we located a small population in January 2003. 
Pedilanthus pulchellus habit
Like its relative P. calcaratus, this species grows in the shade of larger plants. We found it growing in rocky soil beneath very low, dense, seasonally dry tropical forest. 
Pedilanthus tehuacanus
Pedilanthus tehuacanus habit
Most of the stem succulent species of Pedilanthus grow on lowland plains, which are ideal areas for growing crops and building cities. Pedilanthus tehuacanus occurs on the outskirts of the city of Tehuacan and may be in trouble as a result. 
Pedilanthus palmeri
Pedilanthus palmeri inflorescences
This species has very distinctive inflorescences that remind us of ducks. It grows in shady forests in western Mexico from Nayarit to Oaxaca. This population from Oaxaca has inflorescences that lose their bracts very early. 
Pedilanthus palmeri habit
Like P. pulchellus, this species only loses its leaves under extreme conditions, whereas other species such as P. coalcomanensis lose their leaves each dry season. 
Pedilanthus connatus (Euphorbia colligata)
In at least one locality that we have visited repeatedly the plants seem to be disappearing, but we aren't sure why.
Inflorescence of Pedilanthus connatus/ Euphorbia coligata
This species is endemic to the rugged mountains of western Jalisco State, where it often grows in shady canyons. This image shows the particularly attractive cyathium of Euphorbia colligata (P. connatus). Male Euphorbia flowers are extremely reduced, just a pedicel (lower stalk) and the stamen (the anther plus its stalk). In this image, the pedicels of the male flowers are white and the filaments (stalks) of the male flowers are red.
Euphorbia colligata/ Pedilanthus connatus inflorescence with nectar droplet
This image shows the yellow pollen in the male flowers, as well as the red style of the female flower. The clear droplet in the middle of the image is a drop of sweet nectar, which makes us think that some animal, perhaps a humminbird, pollinates this pretty species.

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Instituto de Biología, Universidad Nacional Autónoma de México
Circuito Exterior s/n, Ciudad Universitaria
Copilco, Coyoacán A. P. 70-367
C. P. 04510, México, D. F.

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all material © 2002 Mark E Olson