- Taproot: A single, central root penetrates deep into the soil. It is characteristic of many dicotyledonous plants like carrots and taproot beets.

- Fibrous root system: Adventitious roots emerge from the base of the stem and spread horizontally close to the soil's surface. Fibrous roots are commonly seen in monocots like grasses and cereals.

Secondary root structure (modifications of primary roots):

- Storage roots: Specialized primary roots that store reserve food materials. Examples include carrots (tap roots), sweet potatoes (adventitious roots), dahlia (adventitious roots).

- Prop roots: Additional support for plants is provided by prop roots. They emerge from aerial nodes (stems) and grow downward. They are usually seen in plants like maizes and banyan trees.

- Pneumatophores: These specialized roots grow vertically upwards from a horizontal root system in marshy or aquatic environments. They enhance oxygen absorption from the atmosphere for respiration of waterlogged underground roots. Pneumatophores are seen in plants like mangroves.

- Buttress roots: These above-ground root structures provide extra stability and support, particularly in wide-canopied trees like fig and rubber.

- Climbing roots: These roots allow plants to cling onto surfaces and ascend upwards, as observed in climbers like ivy and money plant (pothos).

- Haustoria: These roots are specialized for nutrient absorption in parasitic plants. They penetrate and connect to the host plant's tissues to extract water and nutrients. Cuscuta (dodder) is a parasitic plant that exhibits this structure.

These root modifications are adaptations to diverse environments and ecological niches, enabling plants to survive under various conditions and compete for resources successfully.