pcplantdb

["Lawrence F. London, Jr." <lfl@intrex.net>]

Richard Morris wrote:

> So it seems that treeness does not really tie well with the typical
> plant systematics. Which leeds to a question "what makes a tree a tree?"
> Is there a tree gene? How come some plants switch it on and other plants
> don't?

A plant is a tree when it is not an annual or a biennial but a very long-lived
perennial. Scientifically

Tree is defined here: http://www.hyperdictionary.com/search.aspx?define=tree 
as:
1. (Bot.) Any perennial woody plant of considerable size
   (usually over twenty feet high) and growing with a single
   trunk.

Note: The kind of tree referred to, in any particular case,
      is often indicated by a modifying word; as forest tree,
      fruit tree, palm tree, apple tree, pear tree, etc.

And you have "tree form" ornamental, native, economic, vegetable, herb, fruit specimen plants normally prostrate, mid height, dwarf, 
semi-dwarf and standard, including such things as rose standards and walking stick collards.

Height or number of trunks doesn't apply as with bonsai, Japanese cutleaf red 
maple
multistem birch, crepe myrtle.

Do plant taxonomists define trees as "woody perennials"?

> Treeness is a very different sort of thing to "has a backbone"
> a feature which is is inherited though a large part of the animal
> kingdom, there was some root animal which had a backbone and all its
> descendants: fishes, amphibians, reptiles, birds, mammals all share this
> property. Flowering plants also fit well with the botanical systematics, 
> all flowering plants (grasses, lilies, orchids, brasicas, roses, oaks
> willows, the pea family, ...) belong to the grouping Angiosperm a well 
> define section of the plant kingdom.

I guess annual, biennial, perennial, perennial-tree would be attributes 
scondary to
taxonomic location.


--
L.F.London
lfl@intrex.net
http://market-farming.com
http://www.ibiblio.org/ecolandtech