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Vein  [ Botany ]
Adjective: Venous
Noun: Venation

Dictionary of botanic terminology - index of names

  A vein is a  vascular bundle (structure formed by xylem, phloem and a bundle sheath) at or near the surface of a leaf (the ribs) that provides supports for the leaf and transports both water and food.  

The vein (vascular bundles of xylem and phloem) extend from the stem, through the petiole, and into the lamina.

(1) Venation (of leaf) [ Botany  - Morphology ]
  The venation is the characteristic arrangement of veins in a leaf.

There are lots of different types of leaf venation that are important for plant identification.
The term venation refers to how veins are distributed in the leaf blade, Usually lamina comprise anastomotic veins that are veins ending in a closed point (e.g. terminating or fused in a leaf apex) while "non"-anastomotic veins which endings are free are quite infrequent.

There are two principal types of venation: parallel-veined and reticulated-veined:

The veins on monocots are almost parallel to the margins of the leaf
whereas in dicots radiate from a central primary midvein that gives
rise to secondary or lateral veins and in turn tertiary veins and

PARALLEL-VEINED-LEAVES: In parallel-veined leaves, numerous veins run essentially parallel to each other and are connected laterally by minute, straight veinlets. Parallel-veined leaves occur most often on monocotyledonous plants. The most common type of parallel veining is found in plants of the grass family, whose veins run from the leaf's base to its apex. Another type of parallel venation is found in plants such as banana, calla, and pickerelweed, whose veins run laterally from the midrib.
RETICULASTED-VEINED-LEAVES: In reticulate-veined leaves (also called net-veined), veins branch from the main rib or ribs and subdivide into finer veinlets. These veinlets then unite in a complicated network. This system of enmeshed veins makes the leaf more resistant to tearing than does a parallel vein structure. Net-veined leaves occur on dicotyledonous plants.
Net venation may be either pinnate or palmate. In pinnate venation, the veins extend laterally from the midrib to the edge . In palmate venation, the principal veins extend outward, like the ribs of a fan, from the base of the leaf blade .

Some different venation patterns of dicots leaves are illustrated below:

Parallel venation:
(2) Venation (Surface patterns) [ Botany  - Morphology ]

A surface repetitive pattern formed by variously coloured or raised linear decoration on a plant surface (e.g. on leaves, fruit, stems, flowers or in other organ... )

Left: Venation (line patterns) on the leaves of Haworthia magnifica v. accuminata

Right: Fine pink vein  on the petals of a flower of the Echinopis hybrid PINK Nr.1

For more details and photography see: Surface pattern





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