off-topic botanical question: Curious about shrubs as a gardening term
James Waddick (Mon, 07 Jan 2008 10:41:25 PST)

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
speaking......
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
USA
Ph. 816-746-1949
Zone 5 Record low -23F
Summer 100F +