1 and only 1 hook per tubercule on fully mature plants

Tobusch Fishhook Cactus (Ancistrocactus tobuschii) Spines
Real County, Texas, 2 March 2008

by Bob Harms ()
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The body (stem) of the Tobusch fishhook cactus is covered with dark green tubercules (the 'nipples'), which are often somewhat flattened on the upper side, sometimes with an apparent very slight groove. (Contrast the light yellow-green, almost cylindrical form of the emerging fruit in the rightmost image.)These are tipped with a whitish villous mass, the aereole.


Aereoles with spine bases.

The spines arise in two series from the areoles. The radial spines, 9—11 in the pictures below, are shorter and narrower than the central spines and tend to spread parallel with the surface outline of the tubercule-covered stem. The larger, wide and flattened central spines are fewer in number, 4 below, and project outward from the aereole; the lowest of these (most distant from the stem apex) with a hook.

The two photo series below show the original photo detail containing the spine set of a single aereole, on the left; and a colored(ized) schematization on the right: radial spines in yellow, the hook spine in purple, other central spines in red.

The surface of the spines is covered with tiny hairs, as may be seen below when backlit.

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