The Pittocaulon Page (succulent Mexican Senecios)

Pittocaulon is a genus of five species of strange shrubs and small trees with broomstick-like branches from dry parts of central and southern Mexico. Along with the genera Telanthophora and Villaseñoria , Pittocaulon was segregated from the enormous genus Senecio of the Sunflower Family (Asteraceae).  In addition to the strange appearance of these plants, Pittocaulon is of interest because of the remarkable range of habitats in which the species occur, from dry highland scrub well above 3000 meters, to tropical dry forest in hot country as low as 300 meters.  Pittocaulon species are conspicuous when they flower at the end of the dry season.

Visit the publications page to find the results of our research on Pittocaulon. Click on the thumbnails below to see a larger version of the photos.

Pittocaulon (Senecio) praecox

Pittocaulon praecox in the dry season This species has the widest range of the genus, and is photographed here on the lava surrounding the Instituto de Biología. This photograph was taken in January.
Pittocaulon (Senecio) praecox flowers
Some species of Pittocaulon  are popularly called "palo loco" or "crazy tree", because they flower at the very end of the dry season when most other plants are suffering the effects of drought. This photograph was taken in March.
Pittocaulon (Senecio) praecox in flower This photograph and the one below were taken in the northern part of the state of Morelos, at nearly 2000 meters above sea level.
Pittocaulon praecox habit The stems of Pittocaulon are very thick and fork into two, three, or four branches after flowering, leading to the strange architecture that can be seen in this image.
Pittocaulon (Senecio) velatum ssp. velatum  
Lone Pittocaulon After P. praecox, the most widespread species is P. velatum. The subspecies velatum is found in western and central Mexico. In this image from Jalisco, a lone individual grows up above the edge of a steep cliff. 
Pittocaulon velatum Pittocaulon praecox branches after flowering. It seems likely that the other species of Pittocaulon branch in the same way. Thus this individual of P. velatum velatum has probably flowered several times.
Pittocaulon velatum, northern Oaxaca
Individuals of P. velatum ssp. velatum can become enormous, growing as members of low tropical deciduous forest. This large specimen was photographed in northern Oaxaca. A younger individual is at left. 
Pittocaulon (Senecio) velatum ssp. tzimolensis
Pittocaulon velatum ssp. velatum habit This subspecies is restricted to extreme southern Mexico. Like most Pittocaulon, it grows on rock, often in very steep situations such as this canyon in Chiapas. 
Pittocaulon (Senecio) filare
Pittocaulon filare inflorescences This species is known only from a single small area in the state of Colima. It is smaller than P. praecox and has densely wooly leaves. Like its larger cousin, P. filare has bright yellow flower heads, of which the bases remain for some time after the seeds are shed. 
Pittocaulon filare stem The pith of all Pittocaulon species is often divided into horizontal strata. These strata appear to expand when water is abundant and shrink as the stored water is used through the dry season. This photo was taken at the end of the dry season.
Pittocaulon (Senecio) bombycophole
Pittocaulon bombycophole Only found in a few places in Michoacán and Guerrero states, this species branches sparingly and has a relatively thick trunk and branches. The leaves, like those of P. filare, are covered with white hairs. The population shown here, from Michoacán, consisted of less than a dozen plants. 
Pittocaulon bombycophole on limestone
This species occurs in a remarkable number of situations: The plants at left are growing on exposed bare limestone. The plant at bottom left is shown growing next to a large wild fig tree (Ficus petiolaris) in open tropical dry forest. Finally, the individuals below center was found growing in the understory of dense deciduous forest. The flowers of P. bombycophole are shown at bottom right. 
Pittocaulon bombycophole and ficus PIttocaulon bombycophole in the forest        Flowers of Pittocaulon bombycophole
Pittocaulon (Senecio) hintonii

Pittocaulon hintonii hintonii
This remarkable species is restricted to a few localities in Michoacán and Colima states. ssp. Pittocaulon hintonii ssp. hintonii, shown here, is only known from southwestern Michoacán. This species tends to branch relatively little, forming small treelets in pockets of soil on boulders. This photo and the next were taken in August, during the rainy season.

Pittocaulon hintonii ssp cerrograndensis
Pittocaulon hintonii ssp. cerrograndensis is from the Sierra de Manantlán to the west of the range of the type subspecies. This subspecies tends to grow in more sheltered areas and is often shorter and more branched than ssp. hintonii. With its mop of floppy, somewhat hairy leaves on broomstick like stems, this species is a striking element of the beautiful mid-elevation tropical dry forests of the Sierra de Manantlán.

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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.

(52) 55 5622-9127 fon (52) 55 5555-1760 fax

all material © 2006 Mark E Olson