Life History, Reproductive Morphology and Development of the Antarctic Brown Alga Desmarestia menziesii J. Agardh*
Abstract The life history, reproduction and development of Desmarestia menziesii J. Agardh from Antarctica is described. Unilocular sporangia occur singly or in small groups in the outermost cortical layer of the sporophyte. They are formed by periclinal division of cortex cells into a stalk cell an...
| Published in: | Botanica Acta |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1995
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1438-8677.1995.tb00851.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1438-8677.1995.tb00851.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1438-8677.1995.tb00851.x |
| Summary: | Abstract The life history, reproduction and development of Desmarestia menziesii J. Agardh from Antarctica is described. Unilocular sporangia occur singly or in small groups in the outermost cortical layer of the sporophyte. They are formed by periclinal division of cortex cells into a stalk cell and the sporangium initial. Meiospores germinate into dioecious microscopic filamentous gametophytes. As in other perennial Antarctic species of the Desmarestiales, gametangia are formed in culture under short‐day conditions or in darkness. In nature, juvenile sporophytes should therefore be formed in winter. They develop only attached to the oogonium. At first they are uniseriate and elongate by means of an intercalary meristem located in their middle part. Laterals are formed predominantly in this region, and they subsequently give rise to secondary laterals. The branching pattern is opposite to alternate in both young and adult plants. Cortication of the main axis is initiated by filaments growing out from the lowermost cells of the primary laterals. In sporophytes of this developmental stage the meristem of the main axis is confined to a small region where cortication starts and above. Lateral branches elongate and become corticated in the same way as the main axis. In mature plants, cells of the inner cortex can become meristematic again and form a meristoderm which contributes to axis thickness by periclinal and anticlinal divisions. The observations are discussed in relation to possible evolutionary relationships in the genus Desmarestia and in the order Desmarestiales. |
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