Haworthia flowers – some comments as a character source.

M B Bayer, PO Box 960, Kuilsriver 7579, RSA

Introduction:

The object of this essay is to discuss where we are now with respect to classification of Haworthia. Despite my comments and observations stretching over 50 years, there are still taxonomists writing and arguing on the basis of method and practice that generated the anarchy of names that existed at the start of my involvement. This method is what is probably referred to as “typological” i.e. there is a single herbarium specimen and anything that departs from this in some mind catching way is a different and thus needs a new name. At the generic level, recent DNA studies show that Haworthia is indeed three separate entities (the subgenera), and that these cannot be rationally separated from the aloid genera. Formal classification requires that Haworthia thus be subsumed in Aloe (see Treutlein et al, Rhamdani et al and Daru et al). This is both incomprehensible and anathema to writers and collectors locked into method that does not rest on any insight to what the problem of species actually is, let alone take proper cognizance of the problems that exists at generic level.

Continue reading →

2. THE RACEME. Figures Set 2 show the bases of the peduncles in several collections to again show how variable they are and not only because of plant vigor and current growth conditions. Diameter can vary by a factor of three. Color is variable and the bract spacing and size of bracts as variables must be noted. Fig 6 is simply a robust spike in a population where the flowers were sparsely spaced on the stem with approximately 15-20 flowers per stem, whereas this raceme had nearly 30 flowers. The number can drop to as low as three. In 7917 we noted a single plant with an inflorescence of over 600mm where the average was below 300. Similarly at 7818 there was one colossal inflorescence of 800mm where again the average was between 300 and 400mm. There is a real problem in that the typological attitude is often adopted when making comparisons like this. An extreme example would be to take H. retusa south of Riversdale as typical of the species. These are massive plants (source of ‘Jolly Green Giant’) and the inflorescences are huge with many flowers. This is not typical for the species and especially so if one takes the mountain cliff populations (H. turgida) to be the same species (as I do) where the plants are proliferous and the inflorescences many and reduced. Plants in poor niches and even poor habitats, flower weakly and the inflorescences are reduced. Figs 7 shows varying capsule positions on the stem. Figs 8 and 9 show a distichous and a secund inflorescence and figs 10 to 15 demonstrate the varied spacing of the flowers that is observable even in any one population although the images are for two different accessions. In Fig. 8 the middle flowers are in a single plane and I regret not having observed the leaf arrangement in that specific plant, because this is a distichous arrangement as the low Fibonacci number of a spiral arrangement of the flowers. This may have been reflected in the leaf arrangement too. The spacing and arrangement of the flowers is also a variable and the number of flowers may also vary. Figs 16 to 18 show bud arrangement and the way in which the fish-tail buds have upturned tips. Although the peduncle does continue to lengthen, most of the lengthening takes place in the flower producing area and towards the upper end of the raceme. The peduncle does not always stay straight and may bend slightly at each floret. The number and distance of the flowers along the peduncle may affect bud packing just as peduncle formation in the rosette results in the appearance of a groove on the leaf face. This is a secondary physical phenomenon and is not an inherent “character”. The leaf keel for example may also be influenced just by physical leaf-packing. A peduncle of a flower from the centre of a plant will have a many angled base, but one arising from a leaf axel only 2-angled. Generally the raceme is indeterminate, meaning that it does not end in a pedicel and flower. But I have seen an individual raceme of H. floribunda with a terminal flower. This exemplifies our problem where characters one might think could be used to determine even genera, are variables at species level.

Continue reading →

6. THE CAPSULES. Figs 6.1 first size differences that can be found within individual inflorescences. The remaining images show 8 capsules per population for a few populations to show variation in size and shape. The way the capsule ripens and splits is very variable. In some cases the capsule is pinched near the end but the locule tips flare outwards. This has the effect of seeds being retained in the capsule. In others the locules flare regularly and symmetrically from the base and the seed is all easily released. In the Van Reenen Crest populations the capsules were inclined to be a reddish hue. But colour can vary depending on the ripening process and they also bleach with time. Fig.6.4 7978 shows this in capsules drying after the peduncle was taken, and retaining their greenish colour. In H. floribunda the capsules are smaller and it appears that they may flare at the tips more in splitting and be coarsely crispate. This is not always the case but it is a tendency in the smaller capsules to do this. Fig. 6.7 is of capsules in 7910 H. floribunda, Rietkuil; compared against 7913 H. mirabilis also Rietkuil east of Swellendam. It is quite evident that even a capsule structure as apparently characteristic as in H. floribunda, is replicated in a different species. Fig. 6.8 is of 7955 Van Reenens Crest, and 7262 south of Greyton. I thought the capsules of 7955 were smaller, reddish coloured and slightly rougher than those of 7262. But the capsule structure in the entire genus is very similar to those shown on this figure and it is just not conceivable that some feature will stand out and resolve issues that exist in respect of the entire group.

Continue reading →