ADAPTATIONS OF EPIPHYTES AND HALOPHYTES

BY

JAYALAKSHMI P S

6302

PLANT ADAPTATIONSPlants can survive in many extreme environments.

In order to survive in such environments, these plants need to have adaptations.

Here ,it deals with epiphytic and halophytic adaptations.

EPIPHYTES These are mainly small shrubs or herbs

attaching themselves to trunks and

Branches, without putting down roots

in soil.

In this way, they can grow high up in

the canopy layer and capture sunlight

to carry out photosynthesis.

They are harmless to the host.

Epiphytes have aerial roots to capture

moisture from the air.

MORPHOLOGICAL ADAPTATION

Roots are well developed. Three types of roots present. 1.absorbing roots (absorbs minerals and nutrients from host) 2.clinging roots(firmly fix to host) 3.aerial roots.(spongy in nature & absorbs atmospheric moisture) Stems in some epiphytes are succulent and leaves are reduced in

number.

ANATOMICAL ADAPTATIONS Thick cuticle Sunken stomata Surface of aerial roots are not cutinized. Water storage tissues seen in succulent types. Aerial roots posses greenish, white thin walled massive

tissues called VELAMEN. Cells of velamen are hygroscopic and absorbs moisture from

air. Their cell wall posses spiral or reticulate thickening & does

not posses protoplasm. Distinct exodermis present below velamen Vascular system well developed. Cortex is parenchymatous

epidermis

velamen

exodermis

Air chamber

cortex

Vascular bundle

PithT.S of VELAMEN ROOT

HALOPHYTES 80% of the earth is covered by saline water Very few plants are able to tolerate saline conditions without

serious damage Plants that survive in saline environments are termed halophytes Most halophytes prefer saline conditions but can survive in

freshwater environments Most halophytes are restricted to saline environments. EG. Rizophora, Avicennia, Sonneratia. They posses STILT ROOTS and BUTTRESS ROOTS. They produce negatively geotropic breathing roots-

PNEMATOPHORES. Seeds germinate before their dispersal and germinated seeds fall as

seedlings and grow on suitable substratum. Secrete SALTS & posses water storage tissues.

MORPHOLOGICAL ADAPTATION STILT ROOTS are also called as prop roots Arise from aerial branches which enter the layers of soil. Helps efficient anchorage of plants.

STILT ROOTS

ROOT BUTTRESS

PNEMATOPHORES OR BREATHING ROOTS are produced from horizontal roots.

Negatively geotropic and posses air pores or lenticels Gaseous exchange takes place through these pores. Anatomically made of arenchyma bering air chambers.

PNEMATOPHORES

Leaves are thick leathery and glassy. Densely covered with branched or unbranched hairs. Fruits and seeds well adapted for dispersal through air and

water. Light weighted and bears air chambers. Viviparous germination. Each seedling consists of club shaped hypocotyle and

downwardly projecting radicle.

ANATOMICAL ADAPTATIONANATOMY OF ROOT ANATOMY OF STEM

LEAF ANATOMY

Physiological Adaptation

High rate of transpiration Release dissolved salts as exudates. Produce additional shallow roots for

water absorption.

Osmotic conc. Of cell sap is high; helps in the absorption of water from saline soil.