Life History of Fossombronia cristula
1920; University of Chicago Press; Volume: 69; Issue: 4 Linguagem: Inglês
10.1086/332649
ISSN1940-1205
Autores Tópico(s)Lichen and fungal ecology
Resumo1. The vegetative body of F. cristula consists of a minute, creeping, rather profusely branched thallus which bears genuine leaves in 2 dorsal rows. 2. The apical cell is dolabrate. Branching is strictly apical. 3. The plants are monoecious, the sex organs occurring in the axes of the leaves. Antheridia and archegonia may occur in the same leaf axis, and there is no time relation in the order of their appearance. They originate from the immediate segments of the apical cell, and their development is strictly acropetal. 4. The antheridia develop according to the usual method found among the anacrogynous Jungermanniales. Variations occur in the order of appearance of the walls in the primary stalk cell. 5. Until the appearance of the first vertical wall, young archegonia cannot be distinguished from young antheridia. The first transverse division in the archegonium initial separates the stalk cell from the archegonium proper, and subsequent development follows the usual Jungermanniales type. The cover cell is inactive, 6-8 neck canal cells are formed, and the venter is 2 cells thick before fertilization. The archegonium is of an advanced type. 6. The early divisions of the embryo are transverse, both halves of the fertilized egg contributing to the development of the foot, seta, and capsule. A calyptra 3-4 cells in thickness is formed. 7. The sporogenous tissue is differentiated rather early in the history of the sporophyte. The elaters are rudimentary, and each is homologous with a single spore mother cell, not with a row of them. 8. The sporophyte is primitive.
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