Abstract

MOSCO, Alessandro. Micro-morphology and anatomy of Turbinicarpus (Cactaceae) spines. Rev. Mex. Biodiv. [online]. 2009, vol.80, n.1, pp.119-128. ISSN 2007-8706.

Spines are a striking feature of cacti and display wide variation in size, number, shape, and texture. This study showed that Turbinicarpus species exhibit not only a high variability in the gross morphology of the spines, but also in their micro-morphology. Their surface can be smooth or ornamented with projections that can be low, conical, pinnate, or long trichomes. The epidermis can be continuous, broken up into single cell elements or transversely fissured, the fissures extending deeply into the underlying sclerenchyma. The mechanical properties of the spines are related to their anatomy, here documented for the first time. The woody rigid spines being made up of fibers with thick walls (> 3 µm), while papery or corky spines have a sclerenchyma made up of fibers with thin walls (< 2 µm). Alternatively, spine anatomy can be dimorphic with the outermost layers made up of thin-walled fibers and an inner core made up of thick-walled fibers. Turbinicarpus taxonomy mostly relies on spine features and the newly collected data can contribute to a better understanding of the interspecific relationships. The epidermal features like long trichomes or the lack of ornamentation as well as the modified anatomy of corky spines may be apomorphic characters within the genus.

Keywords : spine anatomy; sclerenchyma; fibers; spine micro-morphology.

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