text: Alternatively, Simpson uses:
  ; Uninervous: Central midrib with no lateral veins (microphyllous), seen in the non-seed bearing tracheophytes, such as horsetails
  ; Dichotomous: Veins successively branching into equally sized veins from a common point, forming a Y junction, fanning out. Amongst temperate woody plants, Ginkgo biloba is the only species exhibiting dichotomous venation. Also some pteridophytes (ferns).
  ; Parallel: Primary and secondary veins roughly parallel to each other, running the length of the leaf, often connected by short perpendicular links, rather than form networks. In some species, the parallel veins join at the base and apex, such as needle-type evergreens and grasses. Characteristic of monocotyledons, but exceptions include Arisaema, and as below, under netted.
  ; Netted (reticulate, pinnate): A prominent midvein with secondary veins branching off along both sides of it. The name derives from the ultimate veinlets which form an interconnecting net like pattern or network. (The primary and secondary venation may be referred to as pinnate, while the net like finer veins are referred to as netted or reticulate); most non-monocot angiosperms, exceptions including Calophyllum. Some monocots have reticulate venation, including Colocasia, Dioscorea and Smilax.
  However, these simplified systems allow for further division into multiple subtypes. Simpson, (and others) divides parallel and netted (and some use only these two terms for Angiosperms) on the basis of the number of primary veins (costa) as follows;
  ; Parallel:
  ; Netted (Reticulate):
  These complex 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.