Primary root is direct prolongation of the radicle. In most dicots it persists and forms the main root of the plant or Tap root forming the Tap root system.

They are woody perennial climbers whose stem twines around the stem of tall trees and grows with them for light and support. Eg: Bauhinia vahlii .

Perennial herbs having a bulb, corm, rhizome or tuber as the underground stem are called geophytes. Eg: Phyllanthus amarus , Cleome viscosa .

(i) Root climbers: Plants climbing with the help of adventitious roots (arising from node). Eg: Piper betel,Piper nigrum, Pothos.
(ii) Stem climbers: These climbers lack specialised structure for climbing and the stem itself coils around the Support. Eg: Ipomoea, Clitoria, Quisqualis.

Lateral roots develop as extensions of the cells of pericycle in the anatomy of the root. Therefore they are said to be endogenous in origin.

i) The arrangement of veins and veinlets on the leaf blade or lamina is called venation. Internally, the vein contains vascular tissues.
ii) Conventionally venation is classified into two types namely, Reticulate venation and Parallel venation.
Reticulate venation
i) In this type of venation leaf contain a prominent midrib from which several secondary veins arise that branch and anastomose like a network.
ii) This type of venation is common in all dicot leaves. It is of two types.
Pinnately reticulate venation (unicostate):
In this type of venation there is only one midrib in the centre which forms many lateral branches to form a network. Example: Mangifera indica, Ficus religiosa, Nerium.
Palmately reticulate venation (multlcostate):
i) In this type of venation there are two or more principal veins arising from a single point and they proceed outwards or upwards.
ii) The two types of palmate reticulate venation are i.
Divergent type:
When all principal veins originate from the base and diverge from one another towards the margin of the leaf as in Cucurbita, Luffa, Carica papaya, etc.,
ii. Convergent: When the veins converge to the apex of the leaf, as in Indian plum (Zizyphus), bay leaf (Cinnamomum) 
Parahel venation
Veins run parallel to each other and do not form a prominent reticulum. It is a characteristic feature of monocot leaves. It is classified into two sub types.
Pinnately Parallel Venation (Unicostate)
When there is a prominent midrib in the center, from, which arise.many veins perpendicularly and run parallel to each other. Example: Musa, Zinger,curcuma, canna.
Palmate Parallel Venation (Multicostate)
i) In this type several veins arise from the tip of the petiole and they all run parallel to each other and unite at the apex, It is of two sub types.
Divergent type:
All principal veins originate from the base and diverge towards the margin, the margin of the leaf as in fan palm (Borassus flabellifer)
Convergent type:
All principal veins run parallel to each other fromthe base of the lamina and join at the apex as in Bamboos, rice, water hyacinth.

Sub aerial stem found in plants with weak stem in which branches lie horizontally on the ground. These are meant for vegetative propagation. They may be sub aerial or partially sub terranean.
Runner: This is a slender, prostrate branch creeping on the ground and rooting at the nodes. eg. Centella (Indian pennywort), Oxalis (wood sorrel), lawn grass (Cynodon dactylon).
Stolon: This is also a slender, lateral branch originating from the base of the stem. But it first grows obliquely above the ground, 'produces a loop and bends down towards the ground. When touches the ground it produces roots and becomes an independent plantlet. eg. Mentha piperita (peppermint), Fragaria indica (wild strawberry).
Sucker: Sucker develops from a underground stem and grows obliquely upwards and gives rise to a separate plantlet or new plant. eg. Chrysanthemum, Musa, Bambusa.
Offset: Offset is similar to runner but found in aquatic plants especially in rosette leaved forms. A short thick lateral branch arises from the lower axil and grows horizontally leafless for a short distance, then it produces a bunch of rosette leaves and root at nodes. eg. Eichhornia (water hyacinth), Pistia (water lettuce).

These plants produce specialized hook-like structures which are the modification of various organs of the plant. In Artabotrys inflorescence axis is modified into hook .

1. Food storage- Eg: Solanum tuberosum, Colocasia and Zingiber officinale.
2. Perennation/reproduction - Eg: Zingiber officinale, Curcuma longa.
3. Water storage - Eg: Opuntia.
4. Buoyancy - Eg: Neptunia.

In certain trees broad plank like outgrowths develop towards the base all around the trunk. They grow obliquely downwards and give support to huge trunks of trees. This is an adaptation for tall rain forest trees. Eg: Silk cotton tree (Bombax), White cotton tree (kapok).