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TLS Online TPP Program

#Id: 10602

III.Vascular plants  (pteridophyta)

Homosporous or Heterosporous

Sexual reproduction- Oogamous

Antheridium-  Sessile and reduced in size

Haplodiplontic-  alteration of generation

Spores produced inside the sporangia on leaves

#XL - R Botany #PLANT TAXONOMY #Part B Pointers
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TLS Online TPP Program

#Id: 10718

#XL - R Botany

Respiratory roots or pneumatophores
The roots of some trees and shrubs growing in saline marshes (mangrove plants) suffer from the lack of oxygen. Atmospheric air enters these roots through the minute pores of special lenticels (pneumathodes) on the exposed root tips.
TLS Online TPP Program

#Id: 10719

#XL - R Botany

Modifications to carry on special mechanical functions
1. Prop Roots- hanging structures that support a banyan tree

2. Stilt roots
Stilt roots of Sugarcane and Maize are supporting roots which arise from the lower nodes of the stem. These roots grow downwards and penetrate the soil and provide mechanical support to the plant.
Ex- Sugarcane  
3.Climbing roots
climbers can climb up their supports as adventitious roots growing from the nodes.
e.g., Pothos (money plant)
TLS Online TPP Program

#Id: 10720

#XL - R Botany

Modification of stem

I.Aerial stem modification

Aerial modification can be classified into tendrils, thorns, and phylloclade. 

Stem tendrils which develop from axillary buds, are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins, watermelon) and grapevines

I.Aerial stem modification

Some plants of arid regions modify their stems into flattened (Opuntia), or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carryout photosynthesis.

Example- Cactus (Opuntia), Sparrow grass (Asparagus), etc. 

I.Aerial stem modification

Axillary buds of stems may also get modified into woody, straight and pointed thorns, hard, spiny structure protect plants from grazing animals.

Found in many plants such as- Pomegranate (Punica granatum), Paper flower (Bougainvillea glabra), Lemon (Citrus limon), etc.

II.Subaerial Stem modification

Subaerial modification can be classified into four types, namely stolon, runner, sucker, and offset. 
TLS Online TPP Program

#Id: 10721

#XL - R Botany
TLS Online TPP Program

#Id: 10722

#XL - R Botany

III. Underground stem modification
TLS Online TPP Program

#Id: 10723

#XL - R Botany

III. Underground Stem modification