Leaf - Anatomy - Major Leaf Tissues - Veins

The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. The pattern of the veins is called venation, and is typically characterized by hierarchical structures with abundant closed loops. They once thought to be a typical examples of pattern formation through ramification, but they may instead exemplify a pattern formed in a stress tensor field.

A vein is made up of a vascular bundle. At the core of each bundle are clusters of two distinct types of ducts (tubes):

  • Xylem: ducts that bring water and minerals from the roots into the leaf.
  • Phloem: ducts that usually move sap, with dissolved sucrose, produced by photosynthesis in the leaf, out of the leaf.
  • A sheath of ground tissue made of lignin surrounding the ducts. This sheath has a mechanical role in strengthening the rigidity of the leaf.

The xylem typically lies on the adaxial side of the vascular bundle and the phloem typically lies on the abaxial side. Both are embedded in a dense parenchyma tissue, called the pith or sheath, which usually includes some structural collenchyma tissue.

Read more about this topic:  Leaf, Anatomy, Major Leaf Tissues

Other articles related to "vein, veins":

Cobalt Silver Rush - Rush
... On his second day he found a vein, and staked it with another prospector, Alex Longwell ... Immediately thereafter he found a second vein, staking it for himself, while Longwell went off to stake another of his own ... worth of ore was shipped, but the obvious surface veins were mined out ...
Silver Mining In Colorado - Central City-Idaho Springs District
... Silver veins were discovered in the Central City-Idaho Springs district a short time after lode gold was discovered in 1859 ... However, mining the silver veins was delayed for the most part until smelters were built in the late 1860s ... The veins of the district are zoned in a roughly concentric manner, with gold-bearing pyrite veins in the center, and silver-bearing galena veins more common in the outlying areas ...
Sublingual Vein
... The sublingual vein is a vein which drains the tongue ... Veins (emissary, jugular and others) of head and neck (drainage patterns can vary) (TA A12.3.04–06, GA 7.644) External jugular Retromandibular maxillary (pterygoid plexus) · superficial temporal (anteri ...
Smallest Cardiac Veins
... The smallest cardiac veins or Thebesian veins or veins of Thebesius are minute valveless veins in the walls of all four heart chambers and they are often confused with the distinct set of arterial connections ...
Leaf - Morphology - Venation
... namely, craspedodromous, where the major veins stretch up to the margin of the leaf, and camptodromous, when major veins extend close to the margin, but bend before ... penniribbed, penninerved, or penniveined) – the veins arise pinnately from a single mid-vein and subdivide into veinlets ... Three main veins branch at the base of the lamina and run essentially parallel subsequently, as in Ceanothus ...

Famous quotes containing the word veins:

    With veins rolling roughly over quick hands
    They have many clean words to say.
    My grandmothers were strong.
    Why am I not as they?
    Margaret Abigail Walker (b. 1915)

    You know, if this is Venus, or some other strange planet, we’re liable to run into some high-domed characters with green blood in their veins who’ll blast at us with their atomic death rayguns, and there we’ll be with these—these poor old-fashioned shootin’ irons.
    Edward L. Bernds (b. 1911)

    Anyone with any real blood in his or her ... veins cannot help being a fan ....Being a true American and being a fan are synonymous.
    Lulu Glaser (1874–1958)