off-topic botanical question: Curious about shrubs as a gardening term

James Waddick
Mon, 07 Jan 2008 10:41:25 PST
>  So what
>differentiates a shrub from other perennials?  I noticed some authors
>by-pass this problem by calling certain plants  "sub-shrubs."

Dear Friends,
	Although others have commented I think the basic question 
remains untouched. Marguerite, you are mixing multiple categories.

	1.	Shrub is not an alternate to perennial.  Botanically 
	As John Grimshaw explained a 'shrub' is woody plant including 
trees and some vines.

	A perennial is a plant that lives for 2 or more seasons and 
usually blooms annually.

	2.	There is also a horticultural vocabulary being mixed up here.

	A horticultural shrub can be anything that makes a small 
compact 'bush of foliage and flowers. These can be woody such as a 
lilac or rose or herbaceous such as a peony.

	Horticulturally a perennial is herbaceous and deciduous 
(mostly) and can be  bulbs, a true herbaceous plant even some woody ( 
or nearly so) plants.

	So Phygelius is often a woody plant that is grown as a 
perennial 'in some climates'. It can get shrubby looking.

	Yucca is a woody plant that looks shrubby.  An important 
distinction is that tropical plants may flaunt these rules and 
temperate relatives of tropical plants can 'behave' like something 
else. And some plants don't fit very well into boxes. Succulents are 
especially tricky. Cacti are perennials, but 'tree cacti' are not 
generally considered 'woody' plants. Same for tree Dracena, Euphorbia 
etc. Yucca, Aloe, Hawarthia can reach good size, but size alone does 
not make a plant woody or shrubby - tree dahlia, Arundo donax, 
herbaceous Hibiscus can reach 15 ft in one season's growth, and 
annual vines can reach 40 feet in a good summer. None are woody or 
true trees or shrubs.

	Darn pigeon holes.
					Jim W.
Dr. James W. Waddick
8871 NW Brostrom Rd.
Kansas City Missouri 64152-2711
Ph.    816-746-1949
Zone 5 Record low -23F
	Summer 100F +

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