Shape

The spines of Coryphantha spp. are usually round or slightly flattened. Most of them are thicker at the base. Spine strength or thickness and the different shapes of spines are shown in Figs. 14 and 15.

Fig. 13. Scheme of spine formation. Central spine(s) (1), subcentral spines (2), first layer of radial spines (3), second layer of radial spines (4)

Colour

In new growth Coryphantha spines are usually intensely coloured, the central spines being darker than the radial spines. Initially, they are red-brown, but soon become darker to nearly black from the tip. This process is then reversed and the spines become grey from the base, either totally or with the exception of the tips. The change in colour to grey

Fig. 14. Spine thickness. Thin needle-like (a) needlelike (b) thick needle-like (c) subulate (d) thick subulate (e)

is typical for all species of Coryphantha. However, the rate of change varies markedly from one species to another. The radial spines are usually horn-coloured or transparent white at first. Often, the uppermost radials and, more rarely, all radials have dark tips. Moreover, the radial spines become grey from the base, either along the whole length, or with the exception of the tip.

Central Spine(s)

Coryphantha spp. may produce one dominant central spine and up to six subcentral spines, which, following the established practice, we also named central spines. The subcentral spines arise from the upper half of the areole. All central spines arise from the centre of an areole. Words used to describe the number, direction and position of central spines are explained in Fig. 16.

Fig. 15. Shapes of spines. a straight, b slightly curved, c curved, d twisted, e hooked

Fig. 16. Direction and position of central spines. Left porrect (a) and protruding ascending/descending (b), middle upwards, right sideways

Fig. 16. Direction and position of central spines. Left porrect (a) and protruding ascending/descending (b), middle upwards, right sideways

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