Question

General characters of Bennettitales. ​

Answer 1

Answer:

Origin of Bennettitales:

The strobili were typically bisporangiate unlike those of living Cycads. The most common fossils among the Cycadophytes are leaves and it is difficult to distinguish the leaves of Mesozoic Cycadales and Bennettitales from their external features. Their stomatal characters are quite distinctive.

Answer 2

Explanation:

Characteristic Features of Bennettitales:

(a) Vegetative Organs:

1. Plants were un-branched trees, usually 1-2 metres in height, with compressed internodes and ramentum, bearing a crown of large pinnately compound leaves on the top.

2. The trunks were covered with an armour of persistent leaf-bases.

3. The outer walls of the epidermal al cells are sinuous.

4. Guard cells and subsidiary cells are syndetocheilic, i.e., are produced by the division of the same initial.

5. The anatomical structure of the stem shows a thick cortex, a broad pith and narrow vascular cylinder composed of collateral bundles with exarch xylem.

(b) Spore-Producing Organs:

1. Flowers unisexual or bisexual in strobili.

2. Microsporophylls frond-like forming a loose cone.

3. Megasporophylls are not leaf-like, but found in specialised cone-like structure

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