HERB AND TREE 21 



(2) Periblem, forming the cortex; and 



(3) Plerome, forming the fibrovascular elements. 



Duration of Steins. — Herbaceous, dying down to the ground at 

 the dose of the season. 



Annual, an herb whose life terminates with the season. 



Biennial, where the stem dies at the end of the first season, the 

 underground parts perfecting themselves and retaining their vitality 

 to the next season, when seeds are produced and the plant dies 

 completely. 



Perennial, when the underground parts retain their vitality 

 indefinitely. 



Above-ground Stems. — -A twining stem winds around a support, 

 as the stem of a bean or Morning Glory. 



A CULM is a jointed stem of the Grasses and Sedges. 



A climbing or scandent stem grows upward by attaching itself 

 to some support by means of aerial rootlets, tendrils or petioles. 



The SCAPE is a stem rising from the ground and bearing flowers 

 but no leaves, as the dandelion, violet, or blood root. 



A tendril is a modification of some special organ, as of a leaf 

 stipule or branch, capable of coiling spirally and used by a plant in 

 climbing. Present in the Grape, Pea, etc. 



A SPINE or thorn is the indurated termination of a stem tapering to 

 a point, as the thorns of the Honey Locust. 



Prickles are outgrowths of the bark only and are seen in the roses. 



A stolon is a prostrate branch, the end of which, on coming in con- 

 tact with the soil, takes root, so giving rise to a new plant. Ex. : Cur- 

 rant and Raspberry. 



An undershrub or suffruitcose stem is a stem of small size and 

 woody only at the base. 



A shrubby or fruitcose stem is a woody stem larger than the pre- 

 ceding and freely branching near the ground. 



Herb and Tree 



A tree is a perennial woody plant of considerable size (20 ft. or more 

 in height) and having as the above-ground parts a trunk and a crown of 

 leafy branches. 



An herb is a plant whose stem does not become woody and perma- 

 nent, but dies, at least down to the ground, after flowering. 

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