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1 January 2010 Wide-band tracheids (WBTs) of photosynthetic and non-photosynthetic stems in species of Cactaceae
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Abstract
The absence of WBTs and wood polymorphisms in some species of the Caryophyllales may be related to the particular area of plant analyzed. The present research has the objective of studying the photosynthetic and non-photosynthetic stems of different species and stages of differentiation to register wood polymorphisms and to understand the distribution and occurrence of WBTs. Wood polymorphism was observed in the non-photosynthetic stem of young and adult plants of Opuntioideae and Cactoideae and is also found in the photosynthetic stem of young plants of some species of Cactoideae. Cactoideae present WBT/fibrous dimorphic wood that can be related to cambial variation associated with growth habits and plant development. As expected, in the photosynthetic stem of the adult columnar cacti the wood is monomorphic fibrous in which WBTs were not found. This wood contains a great amount of fibers due to necessity of the mechanical support. In contrast, the globular species do not possess fibers in this area of the stem in either adult or young plants. Opuntia monacantha Haw. had non-fibrous wood in which WBTs were observed in the axial system and in the inner parts of the rays. Fiber clusters were present in the axial system. This wood represents a variation in the wood types described for Opuntioideae. Also, in O. monacantha, cells similar to the WBTs were observed in the pith, which can be interpreted as variation in the morphogenic processes during the ontogeny of the plant, probably a case of homeosis. Monomorphic fibrous wood without WBTs was found along the entire stem of Pereskia bahiensis Gürke. This feature has been observed in other pereskias, and in addition to the others, indicates its proximity to the ancestral cacti.
Emilia Arruda and Gladys Flávia Melo-de-Pinna "Wide-band tracheids (WBTs) of photosynthetic and non-photosynthetic stems in species of Cactaceae 1," The Journal of the Torrey Botanical Society 137(1), (1 January 2010). https://doi.org/10.3159/09-RA-052.1
Received: 9 September 2009; Accepted: ; Published: 1 January 2010
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