PLANT ORGANS AND ORGANISMS 
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etc. (2) Tendriliform by thread-like modification and sensitivity 
to contact of a side branch as in Passion flower, Squash, etc. (3) 
Spiny, by checking and hardening of a branch that may then become 
defensive ecologically as in hawthorn, honey locust, etc. (4) 
Aerial tuberous, in which one or more internodes enlarge above 
ground and store reserve food as in pseudobulbs of orchids, Vitis 
gongylodes, etc. (5) Subterranean tuberous in which a subter- 
ranean stem or branch enlarges as a food-storing center: (a) annual 
type, tuber as in potato, etc., corm as in crocus, etc.; (b) perennial 
type, bulbs as in lily (scaly) and onion or hyacinth (tunicated). 
(6) Phylloid or leaf-like in w r hich flattening branch expansion occurs, 
when leaves become reduced in size as in Asparagus, Ruscus, etc. 
(7) Cactoid, in which reduced condensed branches or stems 
become swollen for water (and food) storage as in Cacti, Euphorbia 
sp., etc. 
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. 
Examples: Ivy, Grape, etc. 
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 epidermis and cortex 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. Examples: 
Currant and Raspberry. 
An herbaceous stem is one which is soft in texture and readily 
broken. Example: Convallaria. 
An undershrub or sujf'ruitcose stem is a stem of small size and 
woody only at the base. Examples: Bitter-sweet, Thyme, etc. 
