Pachypodium Habitats - Environmental Conditions

Environmental Conditions

The plants on outcrops, steep hills, and inselbergs are subjected to fluctuating moisture, high winds, and extremes in temperatures. This exposure occurs because, in the case or outcrops and inselbergs, all plants typically are growing in fissures that often have shallow soil and are exposed within the landscape. Pachypodium typically grows in frost-free areas with the exception of P. bispinosum and P. succulentum. The latter two species can sustain winter temperatures reaching into -10°C).

The regions where Pachypodium biotypes exist are (a) situated between sea-level and 2000 meters and (b) are defined by the effects of temperatures. Without exception, all Pachypodium share in a preference for sunny, xeric habitats. Their exclusion from humid forests is almost entirely the case except where "inselbergs" surge above the humid, forest canopy: an example of Pachypodium response to micro-environments than larger vegetative types.

Only plants with special adaptations to extreme drought can survive exposed rocky habitats. Plants with special morphological adaptations produce offspring that can bear the intensity of these arid, xeric, exposed micro-environments. Pachypodium employs two mechanisms to adapt to these conditions:

• Spinescent: The presence of spines that collect moisture in fogs and dews and point downward so that moisture falls to the ground at the base of the plants.
• Pachycaule Trunks: The use of an abnormally thickened trunk or stem of various shapes to store water in times of drought.

In some instances, the pachycaule trunks are geophytic and exist underground as is the case for Pachypodium bispinosum and Pachypodium succulentum.