Straight out of Seussville

At first glance this photo seems fake. However, I assure you this is indeed a real plant. Meet Pachypodium namaquanum, the elephant's trunk. This bizarre member of the family Apocynaceae can be found growing in the dry rocky deserts of Richtersveld and southern Namibia in South Africa. Although it may seem better suited for life in a Dr. Seuss book, I assure you that all aspects of this plants strange appearance enable it to live in some of the harshest climates possible for a plant.

During the spring and summer months (November - March) temperatures in these regions can reach upwards of 50°C (122°F). It doesn't rain much either. What little water this plant does receive comes in the form of fog rolling in from the coast. The plants seem to prefer to grow on the most exposed slopes possible, favoring spots where sun and wind are at their worst.

As such, everything about P. namaquanum seems to be focused on water conservation. The most obvious feature is that swollen trunk. Covered in sharp tubercles, it serves as a water storage organ. These "trees" remain leafless during this time as well. This keeps valuable water reserves from evaporating in the summer heat.

There is at least one aspect of this plants physiology that seems to stand in the face of the harsh desert environment. Anyone who has observed these plants in the wild may have noticed that their tips all seem to be pointing northwards. What's more, this inclination usually ranges between a 50° and 60° angle. This is strange because most desert plants usually prefer to minimized their exposure to solar radiation rather than face it head on.

The reason for this becomes more apparent with the onset of fall. Come April, the climate of these regions becomes a bit more mild. Also, the sun begins to dip below the horizon for longer periods of time. It is around this time that the plant will produce leaves. A single whorl of velvety leaves is emerges from the very tip. Winter is the active growing time of this species. It is also the time in which it reproduces. Attractive yellow and red flowers spray out from between the leaves.

Because the success of the species is reliant on this relatively short growth period, the plant aims to maximize its gains. This is where the northern inclination comes into play. This orientation maximizes the amount of sunlight the leaves and the flowers receive. In this way, the leaves and flowers absorb twice as much sunlight than if they were vertically oriented. It is thought that the sunlight warms the flowers as well as brightens their display, making them impressive targets for local pollinators.

Like most members of this family, seeds are produced in pods and are borne on silky hairs. The slightest breeze can carry them a great distance. Though germination comes relatively easy to this species, it is nonetheless declining in the wild. Mining and livestock have taken up a lot of their available habitat. Poaching is second to these threats as its strange appearance makes it highly sought after by greedy gardeners.

Photo Source: Curious Botanicals (http://bit.ly/1PFhnzj)

Further Reading:
http://www.iucnredlist.org/details/31142/0

http://link.springer.com/article/10.1007%2FBF00329426#page-1

http://www.plantzafrica.com/plantnop/pachynam.htm