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#sporangium development

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Plant Classification

Eusporangiate sporangia are characterized by

Eusporangia represent ancestral sporangial type observed in lycophytes, Psilotum, Tmesipteris, Equisetum, and eusporangiate ferns Ophioglossum, Botrychium, Marattia and Angiopteris. They develop from several initial cells producing several wall layers, thick multilayered wall, relatively large volume containing hundreds to thousands of spores, and generally lack specialized annulus with explosive mechanism, dehiscing via simple slit or apical pores. Leptosporangia contrast with single initial, thin wall, few spores and differentiated annulus for explosive dehiscence enabling efficient wind dis

Ref: Bower Classification of Ferns; Kramer & Green 1990 Fern morphology; Raven Ch 20

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Plant Classification

Leptosporangiate sporangia develop from

Ontogenetic difference fundamental to fern systematics distinguishes sporangial types by initial cell number. Leptosporangium initiates from single epidermal cell that divides periclinally to form stalk cell and capsule mother cell, later differentiating wall, tapetum from inner wall layer, and sporogenous tissue producing thin-walled capsule with few spores. Eusporangium arises from group of initial cells including both archesporial and parietal layers from several cells resulting in massive structure. Single-cell origin explains small size and presence of annulus-mediated catapult mechanism

Ref: Bower 1881 Leptosporangiate development; Foster & Gifford Comparative Morphology

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