All pictures taken 12 August 2008, between 3.43 and 4.00 pm.
Succulent plants may store water in any organ of the plant body. Usually, leaves or stems are used for this purpose, but water can also be stored in the roots.
For this reason we speak of leaf, stem and root succulents. In certain plants the distinction is not so clear-cut, because they use more than one organ for water storage. The subject of this post is a case in point.
The first four pictures were made in winter and spring (between mid July and mid October) and clearly show that the species is a leaf succulent.
Or, so it would seem. The last two photos were made in summer (late January). In #5, most of the leaves have disappeared and the plant was only found because the fruits stand out against the background. In #6, the knife points at a plant at either side of it and here too, very little of the leaves is left.
This begs the question how these plants can survive the drought and heat of the remaining summer period. For the answer we have to go beneath the surface (literally). When we do that, we will find a nice fat tuberous rootstock with enough storage capacity for the plants to aestivate (spend the summer in a dormant state).
The species is only found in a small area near Laingsburg, where most of the rainfall occurs in winter.
To give you some idea of the size of the plants: the leaves are up to about 20 mm long, 8 mm wide and 4-4.5 mm thick.
Deilanthe comprises only three species and is usually incorporated in Aloinopsis.
D. hilmarii has erect leaves about as wide as thick.
D. peersii and D. thudichumii have more spreading and much wider leaves. They are in fact so similar that the Illustrated Handbook of Succulent Plants tells us that they are distinguished only by
–1 the fact that the flowers of D. thudichumii are open between 3 p.m. and 9 p.m. and those of D. peersii between 8 p.m. to 2 a.m.
— 2 some differences in flower morphology
— 3 different pollinators.
Not surprisingly, the book also suggests that D. thudichumii “may therefore be better placed as a subspecies in D. peersii”.
D. peersii, like its siblings, produces a very fat rootstock with quite short stems, each forming only one pair of velvety leaves per season. The plants occur from Laingsburg in the southwest to Fauresmith in the northeast. The rainfall is mostly in summer.
Although the species is widespread, it is not well known. It is probably often overlooked because the plants are low on the ground and the dark grey or brownish leaves are similar to the surrounding shale.
The first picture was taken near the eastern entrance to the Anysberg Nature Resereve (26 Sept. 2006). The other two show plants growing next to the road from Klaarstroom to Willowmore, just east of the provincial border (26 Dec. 2012).
In a recent post (Cover up, 14th Jan.) I discussed how spines, hairs etc. help succulents conserve water. In some families we also come across plants where the leaves are (partly) covered in warts, papillae or tubercles. Although these are often highly decorative, it seemed likely to me that they would first and foremost serve a useful purpose. After doing a bit of research I came up with some interesting information.
It appears that the presence of these projections on stems or leaves has an advantage for the plants in that the breathing pores are hidden in the lower areas between them. This diminishes transpiration and protects the plants from dehydration.
In the case of warts, there is an additional advantage: their epidermis is rich in crystals and lies over cells that store up tannin. This combination makes the plant rather unattractive to herbivores.
In the following two species the names make no reference to things like warts or tubercles, but it is clear that this is not because of lack of these.