Question

Which of the following order is not included in Stachyospermae?

• A. Cordaitales
• B. Ginkgoales
• C. Cycadales
• D. Coniferales

Hint:

To remember this classification, break down the names:

\textbf{Stachyospermae} = Stachys (Stem/Axis) + Sperma (Seed) \(\rightarrow\) Seeds on stems. (Think of conifers, Ginkgo).
\textbf{Phyllospermae} = Phyllo (Leaf) + Sperma (Seed) \(\rightarrow\) Seeds on leaves. (Think of cycads and seed ferns).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The question is based on an older classification system of gymnosperms. This system, proposed by botanists like Sahni, divided gymnosperms into two major groups based on the position of the ovules:

Stachyospermae: Ovules are borne on a stem or axis ('stachys' = spike/axis, 'sperma' = seed). This group is characterized by having simple, often needle-like or fan-shaped leaves.
Phyllospermae: Ovules are borne on leaves or leaf-like structures ('phyllon' = leaf, 'sperma' = seed). This group has large, frond-like leaves.
Step 2: Detailed Explanation:
Let's classify the given orders according to this system:

Cordaitales: An extinct order of gymnosperms considered ancestral to conifers. They had ovules borne on axes, placing them in Stachyospermae.
Ginkgoales: Includes the living {Ginkgo biloba}. The ovules are borne on stalks (axes), placing this order in Stachyospermae.
Coniferales: The conifers (pines, firs, etc.). Their ovules are borne on scales that are considered modified shoots or axes, placing them in Stachyospermae.
Cycadales: The cycads. Their ovules are borne on modified leaves called megasporophylls. This leaf-borne ovule characteristic places them in the group Phyllospermae, not Stachyospermae. Other members of Phyllospermae include Pteridospermales (seed ferns).
Step 3: Final Answer:
Cycadales is part of Phyllospermae, not Stachyospermae. Therefore, it is the correct answer.