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Journal Article

The Embryo Sac of Physostegia

Lester W. Sharp
Botanical Gazette
Vol. 52, No. 3 (Sep., 1911), pp. 218-225
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Page Count: 10
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1. The archesporium of Physostegia consists of a single hypodermal cell, which, without formation of parietals, functions as the megaspore mother cell. 2. The megaspore mother cell by two successive divisions gives rise to a row of four megaspores; the chalazal one enlarges and gives rise to the embryo sac, while the other three disorganize. 3. The mature embryo sac contains an egg, two synergids, three antipodal cells which multiply to several, and two polar nuclei which fuse. 4. During the formation of the embryo sac a lobe develops from near its chalazal end, so that the sac consists of two distinct parts joined by a narrower portion. 5. Double fertilization of the usual type in all probability occurs. 6. The endosperm is cellular from the beginning, the wall accompanying the first division of the endosperm nucleus being longitudinal through the sac. The chalazal portion of the sac, or "endosperm lobe," becomes completely filled with endosperm tissue, which invades and destroys nearly all of the integument; while the micropylar portion of the sac never contains more than a very few endosperm cells, and later disorganizes, becoming completely obliterated by the encroaching endosperm. 7. The first division in the fertilized egg is transverse, and the chalazal cell, which becomes imbedded in the endosperm through the great elongation of the micropylar cell, develops very regularly into a typically dicotyledonous embryo, which displaces nearly all of the endosperm.

Notes and References

This item contains 16 references.

Literature Cited
  • 1
    COOK, Mr. T., Development of the embryo sac and embryo of Castalia odorata and Nymphaea advena. Bull. Torr. Bot. Club29: 211-220. p/s. I2, 13. 1902.
  • 2
    , The embryology of some Cuban Nymphaeaceae. BOT. GAZ. 42:376-392. pIs. i6-I8. I906.
  • 3
    COULTER, J. M., and CHAMBERLAIN, C. J., Morphology of angiosperms, 1903. pp. 96- I3, I77.
  • 4
    GUIGNARD, L., La double fecondation chez les Solanees. Jour. Botanique 16: 145-167. figs. 45. 1902.
  • 5
    HALL, J. G., An embryological study of Limnocharis emarginata. BOT. GAZ. 33:214-2I9. pI. 9. 1902.
  • 6
    HOFMEISTER, WV., Neue Beitrage zur Kenntniss der Embryobildung der Phanerogamen. Abhandl. Königl. Sächs. Gesells. Wiss. 6:533-672. p/s. 1-27. 1859.
  • 7
    JOHNSON, D. S., On the development of Saurutrus cernuus L. Bull. Torr. Bot. Club27:365-372. pI. 23. 1900.
  • 8
    — On the endosperm and embryo of Peperomia pellucida. BOT. GAZ. 30: 1-II. pI. I. 1900.
  • 9
    , On the development of certain Piperaceae. BOT. GAZ. 34:321- 340. p/s. 9, I0. I902.
  • 10
    LLOYD, F. E., The comparative embryology of the Rubiaceae. Mem. Torr. Bot. Club 8:27-II2. p/s. 8-15. 1902.
  • 11
    MURBECK, S., Ueber die Embryologie von Ruppia rostellata Koch. Königl. Svensk. Vetensk. Akad. Handl. 36:1-2I. p/s. I-3. 1902.
  • 12
    SCHAFFNER, J. H., Contribution to the life history of Sagittaria variabilis. BOT. GAZ. 23:252-273. p/s. 20-26. I897.
  • 13
    STRASBURGER, E., Ein Beitrag zur Kenntniss von Ceratophyllum sub- mersum und phylogenetische Erorterungen. Jahrb. Wiss. Bot. 37:477- 526. p/s. 9-II. 1902.
  • 14
    TREUB, M., Observations sur les Loranthacees. Ann. Sci. Nat. Bot. VI. 13:250-282. p/s. I3-20. 1882.
  • 15
    TULASNE, L. R., Nouvelles etudes d'embryogenie vegetale. Ann. Sci. Nat. Bot. IV.4:65-I22. p/s. 7-I8. 1855.
  • 16
    VESQUE, J., Developpement du sac embryonnaire des phanerogames angiospermes. Ann. Sci. Nat. Bot. VI.6:237-285. pIs. ii-i6. 1878.