Volume 5, Chapter 8:- An extension of H. rossouwii

What always comes to mind as I travel through the countryside is the realization of just how much there is to explore.  It takes only an hour of driving from Cape Town to get to the start of Haworthia habitats from any of the three main routes inland.  The roads do not always take in the best routes in respect of suitable or inviting habitats to explore, and besides there is the question of landownership and permission for access.  In recent months my wife and I decided to really make an issue of new exploration and investing time and energy in contacting landowners and looking at places that we have ignored before because of access difficulties.  The result has been a massive set of new finds in respect of populations not previously known to us.  Having other interests such as in Drosanthemum and chameleons has also led us into places we might not have otherwise ventured.

This particular note arises from another chance find. Heidelberg is very rich as far as Haworthia is concerned and I have written quite a lot about the area or referred to populations there. It is a very important area for both H. retusa and H. mirabilis, as well as for H. floribunda and one assumes that the area has been fairly well explored. The Duiwenhoks River offers much suitable Haworthia habitat and I can count at least 30 populations along the drainage system that can be referred to those three species systems.

While checking on two populations of H. retusa ‘nigra’ (the informal way in which I now cite my own combination H. mutica var nigra derived from a G G Smith record south of Heidelberg), we took the opportunity to venture into a field from which we had on the previous occasion been excluded by the presence of ostriches. This was on the farm Diepkloof that I have cited as Morning Star because the two units are now farmed by the same owner and there is also confusion with farms on the east bank of the river also referred to as Diepkloof. The populations we looked at were of H. mirabilis and H. retusa ‘nigra’. The former appears to incorporate H. floribunda in all its populations down the Duiwenhoks River to as far as the change from Bokkeveld shale to Calcareous limestone near Vermaaklikheid.  H. retusa var turgida occurs in various guises along the cliff habitats along the river while in non-riverine flatter areas H. retusa manifests.

We were specifically looking for H. mirabilis or H. retusa when my attention was drawn to an old flower stalk.  There are a few bulb species that have a very similar dry inflorescence as Haworthia so I was a bit cautious when I bent closer to examine its source.  With my search pattern set on the expected, I at first had difficulty focusing clearly on what was there before me – a small form of H. rossouwii (see MBB7803 Figs 1-9).  We started looking wider and found a few plants under bushes until our eyes began to get the message as to what we should be looking for.  To our amazement plants began to spring up all over the place among the dense pebbles.

Why H. rossouwii?  Firstly I have no sympathy with contending classifications that set out to do nothing more than weakly describe variation in the genus in terms of Latin binomials.  My contention is that species are complex systems that need to be understood as highly variable elements that can respond to environmental differences and changes.  H. rossouwii is already known to have an unusually wide distribution range as far as Southern Cape species were concerned.  It is known from north northwest of Bredasdorp and is now known to us at 8 localities southwest of Heidelberg.  Essie Esterhuyzen is reported to have found it at Voorstekop close to the N2 about 90km from the most southwestern population.

I relate “H. elizeae” to H. rossouwii. This was probably first recorded by Derek Tribble from the Bromberg mountain near Stormsvlei, about 40km north of the Bredasdorp populations of this species. There it is in sandstone, unlike the ferricrete and shale habitats the species is found in elsewhere. The Bromberg is also about 90km west of Morning Star. The similarity of the two populations is mostly in respect of size and the flowering time (without suggesting that this is inarguably evidence for sameness). The Morning Star plants are less proliferous in habitat at least, and this may simply be because slope and substrate so strongly relate to vegetative proliferation.  The plants may get to as much as 50mm diameter under the protection of bushes, but in the exposed pebbles they average between 20 and 30mm. The colour seems to be darker green than the yellowish shade of the more general H. rossouwii but we saw plants in their stressed summer garb where there is a strong shade of purple in the plants. It will be interesting to see what the plants look like in the winter.

That this Morning Star population can so readily be allied with the Bromberg population, for me strengthens the view that the ‘systems’ approach to which I more strongly lean, is correct. What does worry we is that the formality of the nomenclatural systems, both botanical and horticultural, becomes very problematic. Essentially the infraspecific categories of subspecies, variety and forma are group categories derived in an era, and for plants, where less variability was known. In many species it has been relatively easy to add horticultural names and this may be because the flowers convey the interest and significance of difference. Where this is transferred to vegetative differences that are so dramatically affected by growing factors it will be very difficult to police. There is of course the additional problem of a taxonomy that is so personalized. Will anyone actually be able to establish when a published name is/was effectively a single plant description and hence a cultivar name as opposed to a group name?  My view is that for the system to work, variability has to be limited and furthermore there is a complication where one now relies on vegetative characters that are so dependent on growing conditions – unlike the flowers of conventional horticultural cultivars. In Haworthia we may have an unusual problem in that many very similar looking species are involved and cultivars (single clones, bred or selected from nature) from different species may be very similar.  I cannot personally see that anyone is going to successfully, meaningfully and usefully disentangle group and individual plant names. In H. rossouwii there might not be a problem as there is not a great deal of difference among the plants of the main body of populations that would excite the taxonomist. There is no doubt that there is enough variability to invite selection by the ardent grower who may develop a special interest in the species. The variant ‘elizeae’ and now ‘Morning Star’ (an informal and workable way of distinguishing the plants) may present problems in that the only way that they might be distinguished is if the collecting data remains attached, and with, any plant cultivated.

Acknowledgement:

I am very grateful to Coetzee and Sarita Uys of Morning Star, to access Diepkloof, and to Gerhard Marx for useful comment and opinion.

 

Picture1 Picture2 Picture3 Picture4 Picture5 Picture6 Picture7 Picture8 Picture9