11
Question
Velamen tissues are found in
Velamen tissues are found in
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Solution
The correct option is A epiphytic roots
Epiphytic or Aerial Roots: Epiphytes are plants that grow upon other plants mainly for support. There are three types of roots in epiphytes — clinging roots (for fixation on plant), normal absorbing roots (for absorbing mineral salts from the crevices of decaying barks of supporting plants) and epiphytic roots (aerial or hygroscopic roots). The aerial epiphytic roots are thick, irregular and hang down in the air. Root caps and root hair are absent. They possess a covering of dead spongy tissue called velamen. It helps the epiphytic roots to absorb water from the atmosphere, dew and rain, e.g., epiphytic roots are found in Vanda.
Floating Roots : A number of adventitious roots arise from each node. Some of them store air, become inflated, project out of water, make the plant light and function as floats. These roots help the plant in floating on the surface of water. e.g., Ludwigia.
Assimilatory Roots: They are green roots which are capable of photosynthesis. In Trapa (water chestnut), the green assimilatory roots are submerged like other roots. They are highly branched to increase photosynthetic area.
Haustorial or Parasitic Roots: These roots are also called sucking roots and occur in parasites for absorbing nourishment from the host. Cuscuta has non green stems and scale leaves. It does not have any connection with the soil. The parasite sends haustorial roots into the host e.g., Duranta, Citrus, Acacia. They make connections with both xylem and phloem of the host, absorbing both water and food. The partial parasite of Viscum (mistletoe) is green. It sends a primary haustorium into the host from which secondary haustoria arises making connections with the xylem channels of the host for absorbing water and mineral salts only.
Epiphytic or Aerial Roots: Epiphytes are plants that grow upon other plants mainly for support. There are three types of roots in epiphytes — clinging roots (for fixation on plant), normal absorbing roots (for absorbing mineral salts from the crevices of decaying barks of supporting plants) and epiphytic roots (aerial or hygroscopic roots). The aerial epiphytic roots are thick, irregular and hang down in the air. Root caps and root hair are absent. They possess a covering of dead spongy tissue called velamen. It helps the epiphytic roots to absorb water from the atmosphere, dew and rain, e.g., epiphytic roots are found in Vanda.
Floating Roots : A number of adventitious roots arise from each node. Some of them store air, become inflated, project out of water, make the plant light and function as floats. These roots help the plant in floating on the surface of water. e.g., Ludwigia.
Assimilatory Roots: They are green roots which are capable of photosynthesis. In Trapa (water chestnut), the green assimilatory roots are submerged like other roots. They are highly branched to increase photosynthetic area.
Haustorial or Parasitic Roots: These roots are also called sucking roots and occur in parasites for absorbing nourishment from the host. Cuscuta has non green stems and scale leaves. It does not have any connection with the soil. The parasite sends haustorial roots into the host e.g., Duranta, Citrus, Acacia. They make connections with both xylem and phloem of the host, absorbing both water and food. The partial parasite of Viscum (mistletoe) is green. It sends a primary haustorium into the host from which secondary haustoria arises making connections with the xylem channels of the host for absorbing water and mineral salts only.
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