The umbels are terminal. 2. The floral parts appear in centripetal succession. 3. The members of the same set arise simultaneously, and there is no confluence of primordia. 4. Glands are present near the axils of the sepals, bracts, and leaves, in some species also on the midribs of the leaves; they are not in pairs, as stated by Engler and Prantl; and are not nectariferous. 5. The tube of the corolla seems to be of toral origin. 6. The adaxial surface of the corolla becomes papillose at the time of blooming. 7. The stamens are remarkable in the development of intercellular spaces. 8. The horn and hood are lateral outgrowths from the filament and composed largely of extremely loose tissue. 9. The fibrovascular bundle of the stamen loops into the hood to near its tip, the curvature beginning after the walls of the tracheids have formed spirals. 10. The elongation of the bundle to form the loop seems to take place by the stretching of the old tracheids and the formation of new ones at their sides. 11. The horn contains no vascular tissue. 12. The top of the "head," and not the functional stigma, is believed to be homologous with the stigma of normal angiosperms. 13. In general Corry's account of the formation of the caudicules, or connectors, and corpuscula is corroborated. 14. The generative cell divides near the tube nucleus, and in the normal manner. The division occurs before the formation of pollen tubes. 15. The pollen tubes from the same pollinium all enter the same ovary. 16. When the pollen tube enters the stigma the tube nucleus is behind the male cells, but it is doubtful whether any reported positions of nuclei in pollen tubes are beyond question. 17. The tube nucleus gets no further than the upper part of the ovary. 18. There is a single integument. 19. The nucellus is a single layer of cells enclosing the sporogenous row. 20. A single hypodermal archesporial cell forms a row of four megaspores without the formation of a parietal cell. Occasionally there is more than one archesporial cell. 21. In the formation of the megaspores the daughter cells do not divide simultaneously, thus perhaps giving a clue to the history of the abridgment of the process in some angiosperms. 22. The female gametophyte develops normally. 23. Double fertilization was observed in Asclepias Cornuti, one of the male cells fusing with the antipodal polar nucleus. This throws doubt upon the view that the attraction is due to near relation of the micropylar polar to the egg. 24. Fertilization may occur before or after the fusion of the polars. 25. A few tracheids were found in the ovules near the antipodals. 26. The fertilized egg rests until the endosperm has become sixteen-celled or more. It is surmised that some reported cases of endosperm division before fertilization may be due to mistaking fertilized for unfertilized eggs. 27. The pappus is composed of single-celled, uninucleate, epidermal hairs. 28. The double wall of the pod has its origin in the rupture of the parenchymatous tissue within the wall of the carpel.
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Theodore C. Frye (1902) studied this question.