m 
obvious ; but the limit between trees and shrubs is not accurate!/ 
ascertained. Linnaeus thinks the bud the best distinction, trees 
having buds, and shrubs no buds; but he immediately acknow¬ 
ledges this distinction to be fallaceous, as many large trees in hot 
climates have no buds. Dr. Alston thinks the difference lies in the 
bark, that trees have an outer and inner bark, (cortex and liber) 
and generally a £ap, (alburnum) but that the covering to shrubs 
Is not a bark but a cuticle or simple skin; but this wants con¬ 
firmation. We can therefore only say that a tree is a perennial 
plant rising to a great hight, with a simple, woody, durable, 
branching, trunk, producing wood fit for timber : The same defi¬ 
nition holds with respect to shrubs, only that they do not rise to 
so great an hight, the trunk not so simple, the branches more 
bushy, and not producing timber. 
An herb is a plant with a succulent stem of stalk, not woody, 
and which generally dies down to the ground every year; and is 
either annual, biennial, &c. or perennial. 
The duration of plants Linnaeus thinks so inconstant, that he 
never employs it in specific differences; In hot climates that 
have a perpetual summer, most plants are trees or shrubs, or at 
least perennial; yet many, when removed to colder climates, loose 
their woody substance, and become herbaceous, and sometimes 
annual, as ricinus, mirahilis, tropceolum, beta, origanum , lavateia * 
&c.—Milne’s Baton-. Diet. 
