Addendum. H. pubescens MBB8011, SW Sandberg.
I need to point out that there is a still earlier article which covers Haworthia maculata (Haworthia maculata <–> Haworthia pubescens) that lays the basis for this discussion. In that article I note the position of the Sandberg to Cilmor and DeWetsberg and intended to include the Sandberg H. pubescens in that article. We could not get landowner contact and so that fell away. However, this problem was overcome and we first explored a Dwyka Tillite outcrop southeast of Sandberg. There is a vast accumulation of windblown sand on the first hill and we saw no Haworthia. There is a smaller hill further to the southeast that is also Dwyka and erosion exceeds wind deposition so smaller non-geophytes do quite well. We found both H. herbacea (see fig.1 MBB8014) and H. pumila there. From there we went to the southernmost point of the Sandberg. A misjudgement landed our vehicle in mud and the drama to get out limited the time we had to explore. We found a lone H. herbacea (fig. 2 MBB8012). Returning a week later we approached the Sandberg from the southwest, and almost immediately on reaching the top we found H. pubescent. Fig. 3 is a view towards Cilmor and DeWetsberg where the plants appear to be intermediate H. pubescens↔H. maculata. The picture is useful to get some idea of the role of geographic and geological considerations. The high mountains in the background are Table Mountain Sandstone and no Haworthia is known there. I am not certain that this is true and G J Payne did tell me that he had seen plants on the extreme lower right and south of the Brandvlei Dam. But also on the absolute distant and absolute left, is the Riviersonderend Mt. That is also TMS. The deep Wolfkloof Valley behind that is the locality for the much unexpected H. herbacea ‘lupula’. (These inverted single commas are not entirely necessary but I use them to underscore my informal use of names that have less reality. The var. lupula is real). The mountains ahead of that last line are Hammansberg on the left and the Moddergat to the right. Between there and DeWetsberg has not so far turned up Haworthia, but this is an exploration problem. Behind the DeWetsberg is also underexplored. H. herbacea does occur between DeWetsberg and behind the mountains on the low right just in the picture and also east of the brickfield out further right. H. maculata is only known in this area along the Nekkies north (further to the right) of the Brandvlei Dam just visible in the picture.
Prior to this exploration H. pubescens was to me only known from the northern part of the Sandberg that lies south of a road going eastwards to Eilandia between Worcester and Robertson. Here H. herbacea does occur on the lower northwest warm slopes. H. pubescens seems to occur only on the upper two ridges and H. herbacea is not known to intermingle with it. This is all Witteberg Sandstone that as a formation overlies Bokkeveld Shale and underlies TMS.
Coming back to the southwest corner of the Sandberg where we found H. pubescens. The plants seem very similar to the species as it occurs to the north. They were very cryptic and often in shady rock retreats where they were really hard to see. It was mid- to late-morning when we were there and the plants were not going to be better exposed as the sun moved further west. Although there was very suitable well-drained habitat lower down on the shaded east slopes, there were no plants and I speculate that this may be because the plants may need the cooling effect of wind movement up on the ridge. The pictures tell the story of variability in respect of a whole range of leaf and rosette characters.
It is worth noting fig. 43 of the dead remains of a plant under a clump of restioid. It seems that seedling survival is closely coupled to early protection giving rise to the concept of nurse-plants. Plants are often very difficult to find because they are so hidden beneath accompanying vegetation. But they do need light and the dynamics of vegetation growth and densification must have quite a big impact on the ageing and survival of plants. It raises again the question of how long do the plants live? For plants like Aloe ferox and A. dichotoma I do have a real experience of a lower limit of about 35 years and a top limit in the several hundred. In the field, the plants seem comfortably ageless.
The really interesting part is this. While I was busy tediously cleaning a plant to photograph it, Daphne called to me to come and see a lighter green plant she had seen. Moving in that direction I saw a plant that registered as H. herbacea but with some hesitation and doubt (see fig.4). I then went to see what Daphne had observed. They seemed less obviously H. herbacea but that seemed to be a logical and conservative opinion (see figs. 5-11). That was until Daphne found two adjacent rosettes at the foot of a restioid clump that left me in no doubt that they were hybrid H. pubescens/maculate (see figs 9-12). These were in bud whereas H. pubescens plants showed no sign of impending flowering. Note the buds are less well developed than MBB8014 further east, even if possibly insignificant. Going back to the other plants we confirmed my doubts. They were a lighter colour and apparently softer texture that we would have expected in H. herbacea. These were the only plants we saw in a space bridging the occurrences of plants of H. pubescens.
|05-11 MBB8013 H. herbaceaXherbacea, Sandberg|
|12-46 MBB8013 H. pubescens, SW Sandberg.|
We did not explore the western slopes where habitat would have been more suitable for H. herbacea and I expect it does occur there. What puzzles me is that so frequently have I found very distinctive hybrids between species in close proximity and very seldom where the species are some distance from one another. I cannot say I have ever found a hybrid in the clear absence of both parents. The example of Astroworthia bicarinata at Lemoenkloof, east of Barrydale, may be an exception where only Astroloba corrugata (syn A. muricata, A. aspera) is present but H. pumila apparently not. Hybridization is thought to be an important element in the “evolution” of new species. I doubt this as it is quite evident that separation into two species is a pre-requirement. If new species have evolved in Haworthia by hybridization, how did they evolve as such in the first place? The answer to me lies in the continuities between populations. I observe, and have experienced of expected continuity between populations. While the Cilmor populations are thought to be H. pubescens↔maculata it cannot be said anymore that they are hybrid, or populations where the morph or drift to discrete elements has not reached a conclusion. The latter is more likely. As there is already apparent geographic continuity of H. maculata and H. herbacea, I was expecting some evidence of a similar relationship between H. herbacea and H. herbacea. So here it is. Hybridization as a factor in speciation in Haworthia does not seem to very likely. It confirms for me that there is a fractal “chaotic” order to species in Haworthia and the reality is that a view of many truly discrete species is a fabrication and a very ill-considered view.
We are always greeted with such kindness and helpfulness that we might have expected this from the Sandberg landowners too. It came in no small measure. Driaan Griesel was most enthusiastic and interested and also helped us with extracting our vehicle from the mud on the one occasion, and then jump-starting it after a flat battery on the second. Our imposition did not so much as touch his view of the day.
(ed. – Bruce made another visit to Southwest Sandberg on 9 December 2012 and includes the following flower pictures. He makes this comment; personal correspondence 27 December 2012.)
I am actually not sure at all about flowering time now. I used to be quite sure of being able to collect seed of pubescens mid-Nov. But I observed at Humansdorp that gordoniana peak flowering could be out by 6 weeks. In any case the plants can produce successive spikes so one can get delayed flowering and added to that energy in the first or the second flower set. I know mirabilis at MacGregor can flower from Nov. thru to March while at Montagu mirabilis can flower as late as April/May. Retusa and geraldii are quite happy to produce flowers in either Spring or Summer and Kobus observed that splendens did that too. Maculata can flower from Sept. thru to late Dec. And each population does its own thing.