In this presentation, concept of epiphytes, types of epiphytes, and adaptations (morphological, anatomical and physiological) developed in them are are explained.

1. Epiphytes
Dr. Ravindra. D. Madhekar
Assistant professor,
Department of Botany,
S. B. E. S. College of Science,
Aurangabad
(Maharashtra)
India

2. • Epiphytes (Epi = above, phyton = plant)
• Those autotrophic plants which grow on the surface of some
other supporting plants and are not permanently rooted in
the soil.
• Absorb sufficient moisture from the atmosphere and mineral
nutrients from the decaying bark of the supporting plants
upon which they are situated.
• Differ from parasites and also from lianas (woody stem
climbers).
• Also called Aerophytes or air plants.

3. • Distribution:
• Grow on the surface of submerged aquatic plants, may be
aerial, on the surface of tree trunks, grow even on the
surface of leaves (i.e., epiphyllous epiphytes).
• Epiphytic vegetation is very rich in moist and cold regions but
poor in dry and cold areas.
• In north-western Himalayas much less in number as
compared to those present in the eastern Himalayas.
• In warm and wet regions, members of the families
Bromeliaceae and Orchidaceae are found in abundance.
• In tropical rain forests, epiphytic species found at the tops of
trees are xerophytic in nature but those occurring at lower
levels are hygrophilous (moisture and shade loving).

4. Morphological adaptations
(i) Root system:
• Extensively developed.
• The roots may be of the
following three types
(a) Normal absorbing roots
(b) Clinging roots
(c) Aerial roots

5. (ii) Stem:
• May or may not be extensively developed.
• Some epiphytes develop succulence in their stems and become
pseudo-bulbous or tuberous
(iii) Leaves:
• Considerable reduction in leaf number.
• Some orchids develop only a single leaf in a growing season.
• Leaves in some may be fleshy and leathery
• In Dischidia nummularia, Platycehum and Aspleniumnidus
leaves are modified into the pitchers.

6. • Dischidia nummularia,
(Asclepiadaceae),
shows peculiar types
of leaf pitchers.
 In family Bromiliaceae, some species develop spoon-like leaves in
rosettes.
(iv) Fruits, Seeds and their dispersal:
 Usually dispersed by wind, insects and birds.

7. Anatomical adaptations
(i) Presence of thick cuticle and sunken stomata:
• These two structures greatly reduce the loss of water from the
plants.
• Generally the surface cells of water absorbing organs (roots and
some leaves) are not cuticularized.
• In succulent epiphytes, thin-walled parenchymatous tissue that
stores water develops extensively.
• The aerial hanging roots of many tropical epiphytes belonging to
the families Araceae and Orchidaceae develop on their surface a
characteristic greenish white thin-walled massive tissue called as
velamen

8. • The velamen is hygroscopic
tissue that rapidly absorbs
moisture from the saturated
atmosphere like a sponge.
• It is modification of
multilayered epidermis.
• Its cells are empty (i.e., dead)
and cell walls show spiral or
reticulate thickenings.
• Inner to the velamen there is
present a peculiar layer called
exodermis.

9. • Exodermal cells are of two types:
• (a) Lignified and thick walled cells.
• (b) Thin-walled cells or passage cells, walls of which are
permeable to water. The velamen absorbs and retains
moisture till that is absorbed by passage cells of exodermis.
• (iv) Other structures are similar to those found in
mesophytes.

10. • Types of Epiphytes:
(1) Protoepiphytes:
 Derive their nourishment partly from the surface of the
supporting plants and partly from the atmosphere. Examples:
Peperomia, Dischidia and some ferns belong to this group.
(2) Hemiepiphytes:
• Grow on the supporting plants in the beginning like true
epiphytes but later on they establish connection with the soil by
their roots.
• Some grow in the soil but their stems die from below upward
and terminal portions live independently like hemiepiphytes.
(Pseudoepiphytes).

11. (3) Nest epiphytes:
• These have appropriate devices to collect large quantity of
water and humus for their own use. E. g Orchids
(4) Tank epiphytes:
• These plants develop fibrous anchoring roots which do not
take part in the water absorption. Leaves, that are variously
modified, absorb water and manufacture food.
• Nidularium, Tillandsia, and other epiphytic species of
Bromeliaceae are common plants of this group.