Q.58 The basal portion of a mature ligule of Selaginella is called as:
1. Basal sheath
2. Lamella
3. Glossopodium
4. Stalk
Selaginella ligules are specialized leaf appendages with distinct morphological regions critical for water absorption and sporangial protection.
Correct Answer
3. Glossopodium – The basal, hemispherical portion of a mature ligule.
Selaginella Ligule Structure
Ligules project from leaf bases in Selaginella (spike moss). A mature ligule comprises:
-
Glossopodium: Basal swollen region of large thin-walled cells, surrounded by glossopodial sheath
-
Ligule body/tongue: Elongated upper portion above glossopodium
Option Explanations
1. Basal sheath
Refers to leaf base wrapping stem, not ligule anatomy. Ligules arise from leaf axil above basal sheath.
❌ Incorrect: Different structure entirely.
2. Lamella
“Lamella” describes thin plate-like structures (chloroplast lamellae, gill lamellae), not ligule basal region.
❌ Incorrect: Wrong morphological term.
3. Glossopodium
Basal hemispherical structure of ligule made of parenchyma cells for secretion/absorption. Diagnostic for Selaginella vs. Isoetes (unicellular ligules).
✅ Correct: Standard botanical terminology.
4. Stalk
Ligules are sessile (no stalk); directly attached via glossopodium. “Stalk” would imply petiole-like structure.
❌ Incorrect: Ligules lack stalks.
| Option | Ligule Relation | Anatomical Accuracy |
|---|---|---|
| Basal sheath | Leaf base structure | ❌ Not ligule |
| Lamella | Thin plate term | ❌ Misapplied |
| Glossopodium | Basal ligule portion | ✅ Correct |
| Stalk | Supporting structure | ❌ Absent in ligules |
Exam Tip: Glossopodium = Ground/base of Selaginella ligule.
