Root Modifications

Most dicots form a tap root system:

radical persists: becomes main root with lateral branches.

Most monocots form a fibrous root system:

radical dies: roots arise from stem tissue (adventitious).

Root modifications to know: adventitious roots, storage tap

root, storage tuberous roots, storage fleshy roots, and

aerial roots.

,

Tap roots (dicots) and fibrous roots which are formed adventitiously (monocots). Modifications - Root © KPU.ca/Hort

Adventitious roots of English ivy, climbing hydrangea, and philodendron (dicots).

Adventitious root arising from the

vascular cambium of the stem

Modifications - Root © KPU.ca/Hort

Adventitious roots on a chrysanthemum cutting (dicot) and on lily bulbs (monocot). Modifications - Root © KPU.ca/Hort

Storage fleshy roots of daylily (Hemerocallis) – a monocot and still is a fibrous root system. Modifications - Root © KPU.ca/Hort

Aerial root on an epiphytic orchid (Phalaenopsis) – a monocot with a fibrous root system. Modifications - Root © KPU.ca/Hort

Storage tap roots of carrot, horseradish, and beet (dicots). Modifications - Root © KPU.ca/Hort

Storage tuberous roots of dahlia (dicot), yam, and of two sweet potato cultivars. Modifications - Root © KPU.ca/Hort

True yam Sweet potato

Genus /

species

Dioscorea spp.

Ipomoea batatas cvs.

Class monocot dicot

Plant Type vine vine

Organ

modification

tuberous roots tuberous roots

dahlia

yam

Ectomycorrhizae formed by five species of fungi (over 2000 spp. can colonize conifers in the

Pinaceae): enhances N,P,K, water uptake, protects root tips from pathogens & desiccation. Modifications - Root © KPU.ca/Hort

Root nodules of alder (which contain Frankia) and clover (which contain Rhizobium). The

bacteria inside can fix atmospheric nitrogen gas and convert it into a form the plant can use

as a source of nitrogen (do NOT confuse with ETM – no fungus can do this!).

alder clover

Modifications - Root © KPU.ca/Hort