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

John Grimshaw
Sun, 06 Jan 2008 23:30:45 PST
 "JamieV." wrote:
> as far as I know, shrub is not a scientific term, rather a gardening
> term that has worked its way into general use.  For myself, a shrub must
> have a permanent set of woody stems and branches that continue into
> growth each season.

Shrub is a perfectly good botanical term (with Latin equivalent, frutex) for 
a woody plant that branches from the base, as opposed to a tree, which is 
technically a 'single-stemmed' woody plant - both of course having the 
"permanent set of woody stems and branches that continue into growth each 
season". There is of course a continuum between shrubs and trees in terms of 
growth form and the distinction is very artificial.

The fact is that we do not possess a precise vocabulary for distinguishing 
plants into growth-form categories and inevitably some taxa are shoehorned 
into slots they do not deserve - Yucca as a shrub being one. They are 
semi-succulent rosette plants with a pseudo-woody base or trunk. 'Subshrub' 
is a horrible term, as Jamie points out, as it's a catch-all name that 
covers anything that isn't really woody but has perennating stems - but 
there is no real alternative in general hortico-botanical terminology.

Phygelius is an excellent example of how plants do not conform to our terms. 
In most of the UK it acts as a shrubby plant, with overwintering softly 
woody stems emerging from the base, although it is often cut back hard in 
spring to stimulate new growth and keep it in bounds. In favoured places 
these stems can persist and can be trained against a wall to form a thick 
stem. In harsher climates, and this includes its native South Africa, 
Phygelius capensis can be cut to the ground by frost and re-emerge each year 
as annual shoots, just like any other perennial.

John Grimshaw

> Marguerite English schrieb:
>> I have been doing some studying about garden terms and have a botanical
>> question.   I was looking at Phygelius information and it was identified
>> as a shrub.  I had previously called it a perennial. 

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