Question

Ptyxis in Cycas is
(a) Simple
(b) Circular
(c) Circinate
(d) None of the above

Answer 1

Hint: A Leaf in bud condition is called ptyxis. It is the way a leaf is folded during its developmental stages. Such type of Ptyxis is seen in the leaves of ferns (Pteridophytes) and Cycas. When their leaves are young they are coiled like the spring. It is coiled to protect the delicate growing tip of the leaf.

Complete answer:
Ptyxis in Cycas is in circinate vernation..
Rolling or folding of individual leaves may be of the following types:
1. Reclinate - when the upper half of the leaf blade is bent upon the lower half. Example: loquat (Eriobotrya japonica).
2. Conduplicate - when the leaf is folded lengthwise and along the mid-rib. Example: guava, sweet potato, and camel’s foot tree (Bauhinia).
3. Plicate or plaited – when the leaf is folded repeatedly longitudinally along ribs in a zig-zag manner. Example: palmyra palm (Borassus flabellifer).
4. Circinate - when the leaf is rolled from the apex towards the base like the tail of a dog, as in ferns or cycas.
5. Convolute - when the leaf is rolled from one margin to the other margin. Example: banana, aroids, and Indian pennywort.
6. Involute - when the two margins are rolled on the upper surface of the leaf towards the midrib of the leaf. Example: water lily, lotus, Sandwich Island Climber (Antigonon), and Plumbago.
7. Crumpled - when the leaf is folded irregularly. Example: cabbage.
So, the correct answer is, ’Circinate.’

Note: In young conditions, the young leaves show circinate ptyxis, like in fern leaves, and remain covered by ramenta. Ramenta are thin brownish chaffy scales upon the leaves or young shoots of some plants, especially upon the petioles and leaves of ferns.