MODIFICATIONS OF STEM :
1.STEM TENDRILS: These are climbing structures of the plant long thin spirally coiled which help the plant to climb these are of following four types:
(a)Axillary : The axillary bud of stem modified into tendril. Ex. Passiflora
(b) Extra axillary: The extra axillary bud form tendril.Ex Cucurbita
(C) Apical bud : The apical bud of successive branches pushed to one side and modified into tendrils. Ex. Grape vine
(d) Floral bud : Upper floral bud modified into tendril.Ex Antigonon.
2.STEM THRONS: The axillary bud of some plants become sharp stiff and pointed called throne . They are endogenous in origin that means having vascular connection.They reduce transpiration and hence water loss is minimum and also protect plant from grazing animals.Ex. Citrus
3. PHYLLOCLADES: In xerophytic plants the leaf modified into spines and then the stem become thick fleshy cylindrical and contain chlorophyll to perform photosynthesis this modified stem is called phylloclade it has unlimited growth.
Ex.Opuntia — In this the stem is modified into jointed branched flat fleshy and succulent leaf like structure . Leaves modified into spines and flower born on nodes.
4. CLADODES: The features of cladode is similar to phylloclades like it is green cylindrical or flat leaf like structure & perform photosynthesis the only difference is it has limited growth.Leaves modified to spines flower arise between two internodes at nodal portion.Ex Asparagus & Ruscus
THALAMUS OR TORUS: it is the swollen portion of the stem of flower .
