species is a leafless stem succulent from
the Sonoran Desert of northwestern Mexico. This photograph is from the
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.
in a remote mountain range in western Mexico in the 1930s.
the information on the herbarium specimen label was so vague that its
location was unknown. We recently located a population of this species,
forms graceful small trees with large, colorful inflorescences, fuzzy
and tuberous roots. This photo was taken in the winter dry season.
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.
fuzzy leaves of Pedilanthus
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 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.
|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 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.|
|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.|
|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.|
|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 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.|
|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.|
|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.|
|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.|
|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.|
|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.|
|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.|
connatus (Euphorbia colligata)
at least one locality that we have visited repeatedly the plants seem
to be disappearing, but we aren't sure why.
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.
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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Universidad Nacional Autónoma de México
Circuito Exterior s/n, Ciudad Universitaria
Copilco, Coyoacán A. P. 70-367
C. P. 04510, México, D. F.
(52) 55 5622-9127
(52) 55 5555-1760 fax