Ticket #3473 (new)

Opened 6 months ago

Remove This Blockage And Restore Your Hearing

Reported by: "Restore Your Hearing" <ClarisilPro@…> Owned by:
Priority: normal Milestone: 2.11
Component: none Version: 3.8.0
Severity: medium Keywords:
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Remove This Blockage And Restore Your Hearing



mplex systems are not used much in morphological descriptions of taxa, but have usefulness in plant identification,  although criticized as being unduly burdened with jargon.

An older, even simpler system, used in some flora uses only two categories, open and closed.

Open: Higher order veins have free endings among the cells and are more characteristic of non-monocotyledon angiosperms. They are more likely to be associated with leaf shapes that are toothed, lobed or compound. They may be subdivided as;
Pinnate (feather-veined) leaves, with a main central vein or rib (midrib), from which the remainder of the vein system arises
Palmate, in which three or more main ribs rise together at the base of the leaf, and diverge upward.
Dichotomous, as in ferns, where the veins fork repeatedly
Closed: Higher order veins are connected in loops without ending freely among the cells. These tend to be in leaves with smooth outlines, and are characteristic of monocotyledons.
They may be subdivided into whether the veins run parallel, as in grasses, or have other patterns.
Other descriptive terms
There are also many other descriptive terms, often with very specialized usage and confined to specific taxonomic groups. The conspicuousness of veins depends on a number of features. These include the width of the veins, their prominence in relation to the lamina surface and the degree of opacity of the surface, which may hide finer veins. In this regard, veins are called obscure and the order of veins that are obscured and whether upper, lower or both surfaces, further specified.

Terms that describe vein prominence include bullate, channelled, flat, guttered, impressed, prominent and recessed (Fig. 6.1 Hawthorne & Lawrence 2013). Veins may show different types of prominence in different areas of the leaf. For instance Piment

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