secondarygrowth213-page14

secondarygrowth213-page14 - • Uniform upward diameter •...

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Secondary Growth in Stems: Wood, Bark and Surface Features - 14 Secondary Growth in Monocots As mentioned previously, monocots generally lack secondary growth and most monocots are small and herbaceous (which is consistent with the lack of secondary growth). However there are some significant exceptions to the overall small size of monocots and there are a number of ways monocots increase in girth with little or no secondary growth. Mechanisms to Increase Girth and Provide Support Many monocots will provide for increases in diameter as the seedling emerges by producing a thickened meristem that produces a wide procambium region. This results in a large diameter base with many strong vascular bundles and much vascular parenchyma. The apical meristem containing many leaf primordia is essentially embedded into the thickened meristem. The unique meristem cap produces stem growth that has:
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Unformatted text preview: • Uniform upward diameter • Thickened parenchyma cells for support • Long lived phloem • Large apex (or tip) providing for o Leaves with large vascular connections that sheath the stem increasing the diameter of the axis Example = Palms Thickened palm meristem Uniform stem diameter in palm • Prop roots develop providing long-term support for the plant (See roots section) Example = Pandanus or corn • Produce a cambium that produces additional vascular bundles, but not a "wood". This increases volume but is not necessarily a "tree-like" organism Example = Agave • Sheath the stem with giant leaves that have extraordinary vascular tissue (vein) connections. Veins, the vascular tissue of leaves, have many sclerenchyma fibers. Often such plants are quite short-lived, although they achieve big dimensions Example = Banana...
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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