WHERE SUBSPECIES MEET

By Keith Green (photos also by the author unless otherwise stated).

 

 

Page 267 of LITHOPS FLOWERING STONES 2005 states that Lithops pseudotruncatella subsp. groendrayensis is “clearly allied to its very close neighbour L. pseudotruncatella subsp. dendritica “. However, I did not realise just how closely allied these neighbours were until I took a Namibian field trip in February 2012. I was part of a group that spent a day exploring two bordering farms to the south of Rehoboth where the two afore mentioned subspecies were known to grow. Our guide was Windhoek resident and Namibian Lithops expert Tok Schoeman and together with my son Christopher and Namibian born but U.K. based veterinary surgeon Roy Earle, our group consisted of four.

Our first stop was on the farm where Professor Desmond Cole and his wife Naureen made their C246 collection of subsp. groendrayensis. As farms in Namibia are huge by European standards, we cannot be exactly sure where the Coles made their collections. However, I had checked with them before we travelled so we could be certain we were in the correct general area. We actually explored two spots on this first farm, the first being very close to a gravel road with attendant goats (Fig 1). As we knew subsp. groendrayensis grew here it was no surprise when we found our first typical specimens. These were growing between brilliant white quartz, and were nicely turgid following recent rain. The faces were typical grey-white, superficially blank and some were tinged with light blue. A number sported old flowers that had withered to a striking red colour (Fig 2), while others were still in bud (Fig 3). We searched further and found plenty more similar plants, but then there was an obvious specimen of subsp. dendritica, and then another and then some forms that were awkward to name. Until that point I was not aware that subsp. dendritica and subsp. groendrayensis ever grew socially, but the plants in front of us were telling a different story. Fig 4 shows three Lithops from this first spot, and along with several others nearby, I struggled to identify the bottom right hand plant.

Fig 1. The general locality of C246 subsp. groendrayensis with local goats (photo: Christopher Green).

Fig 2. L. pseudotruncatella subsp. groendrayensis with fading red petals (photo: Christopher Green).

Fig 3. L. pseudotruncatella subsp. groendrayensis in bud.

Fig 4. Two (or is it three?) specimens of L. pseudotruncatella subsp. dendritica.

Fig 5. Plants of L. pseudotruncatella subsp. groendrayensis within a rock crevice (photo: Christopher Green).

At a second search site, which was a low koppie on the same C246 farm, subsp. groendrayensis was again dominant (Fig 5). However, a few specimens that could only be described as subsp. dendritica were also present. As with the first search area, there were places where the two subspecies appeared to grow as immediate neighbours and Fig 6 shows one of several such examples we discovered throughout the day.

Fig 6. Are all these plants of the same subspecies? (photo: Christopher Green).

We moved on and continued through a “bekslaner” gate onto the farm where the Coles made their C245 collection of subsp. dendritica. The word “bekslaner” or sometimes “smoelslaner” (I was told by Tok) is Afrikaans for a gate that is held in tension on its post and can spring back when un-hooked and hit you in the mouth. It translates in slang English to “trap-smacker”.

Again we cannot be sure of exactly where the Coles searched and made their C245 collection on this vast farm, but our first stop close to the boundary fence again revealed subsp. groendrayensis, although this time there was a greater proportion of subsp. dendritica (Fig 7). Both taxa were growing socially in quartz covered clearings that were protected by some fiercely thorny bushes. We continued further in our 4X4 and having got permission from some nearby farm workers, travelled off road to another promising koppie where we began to explore again. In the vicinity of some lovely Aloe littoralis and among some striking red-brown stained quartz (Fig 8), we quickly discovered Lithops, the vast majority of which were unquestionably subsp. dendritica (Figs 9 & 10). Typical subsp. groendrayensis were also present but in a minority. This proved to be a prolific area for Lithops although their preference for slightly raised koppies and quartz seemed to limit their immediate spread. There were no roads anywhere near us and on the rare occasions when the flies stopped buzzing and the wind stopped blowing, we had complete silence.

Fig 7. A form of subsp. dendritica.

I treasure such places but having expected to see pure subsp. groendrayensis on the C246 farm and pure subsp. dendritica on the C245 farm I was perplexed. I also felt uncomfortable at not being readily able to place some of the Lithops we had seen within either subspecies. I therefore turned to my copy of FLOWERING STONES as soon as time would allow. There the descriptions make it clear that although typical forms of these two subspecies are quite distinctive, occasional specimens can be very similar. A key difference however, appears to be with the channels, although even then occasional specimens of subsp. dendritica can have “very slender obscurely translucent grooves with very few or no rubrications”, and the channels of subsp. groendrayensis can “infrequently constitute a coarse broken network”. Also, rubrications can “rarely” occur in subsp. groendrayensis which “manifest as very obscure subcutaneous dots or very short lines”, and similar patterns are sometimes seen in subsp. dendritica. It follows that these “very similar” plants are part of the dominant population, and I see no reason to think differently based on our limited observations. Clearly we visited an area where the subspecies meet and grow socially, but subsp. dendritica dominates around the C245 locality and subsp. groendrayensis dominates around the C246 locality. We must also remember that the extensive research of the Coles showed a minimal overall morphological and distribution overlap of the two taxa.

Fig 8. The general locality of C245 subsp. dendritica (photo: Christopher Green).

Fig 9. Two habitat subsp. dendritica.

Fig 10. Subsp. dendritica with seed capsule.

Fig 11. A pale example of subsp. dendritica from around the C384 locality.

Fig 12. A marked example of subsp. dendritica growing close to the plant in Fig 11.

We made one further visit that day which was to the general area where the Coles made their C384 collection of subsp. dendritica. Although it appeared this locality had suffered due to gravel extraction (probably for road construction), we did find Lithops (Figs 11 & 12). This was something I failed to do when previously I searched this very spot with my wife Debra in 2009. The Lithops we found were quite variable, but I was comfortable they were all subsp. dendritica and my thoughts were backed up all the more once I had studied the Cole descriptions once again.

Before I left Namibia I was also able to briefly re-visit the locality of L. gracilidelineata subsp./var. gracilidelineata C309 where I had searched with the Coles in 2007 (Fig 13). Back then conditions were extremely dry and we only found one specimen. This time however, I was more successful. Via stabilisation the unpublished “fuscous” form from this locality, gave rise to the var. gracilidelineata ‘Cafe au Lait’ cultivar in1995. In the establishment article that appeared in PIANTE GRASSE SPECIALE, Steve Hammer aptly described it as having a “combination of whipped cream islands floating on a cappuccino sea”. Fig 14 shows some lovely examples I had photographed a few days earlier in the collection of Tok Schoeman.

I send sincere thanks to Christopher and Roy for accompanying me to the localities and special thanks to Tok for his guidance, hospitality and extensive local knowledge.

Fig 13. L. gracilidelineata subsp./var. gracilidelineata ‘Cafe au Lait’ originated here (photo: Christopher Green).

Fig 14. L. gracilidelineata subsp./var. gracilidelineata ‘Cafe au Lait’ in the Schoeman collection.

References

Cole, D.T. & Cole, N.A. (2005) Lithops Flowering Stones. Milano: Cactus & Co.

Hammer, S.A. (1995) ‘New Cultivars in Lithops’, Piante Grasse Speciale Supplemento al n. 4, 15 (4): 46-50.