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TORREYA 



Vol. 28 No. 1 



January-February, 1928 



THE PERIOD OF ANTHESIS IN HIBISCUS 

 Alexander F. Skitch and Robert L. Blrwell, Jk 



A small fresh-water marsh, separated by a narrow, wooded 

 neck of sandy soil from the brackish waters of the estuarine 

 Severn River on the western shore of Maryland, was from late 

 July until mid September bright with the showy blossoms of 

 hibiscus. Growing side by side in the oozy, black soil were 

 plants which produced flowers of four different color combina- 

 tions. The crimson-eyed hibiscus {Hibiscus oculiroseiis Britton), 

 named from the crimson patch in the center of the large, white 

 corolla, was present in the greatest abundance. Scattered 

 among this grew a hibiscus with a delicately rose-tinted corolla, 

 the swamp rose-mallow (77. Moscheutos L.). In addition to these 

 were plants which produced flowers with pure white corollas, and 

 others the petals of which had the rose tint of the rose-mallow, 

 except for the crimson eye of H. oculiroseus at the center of the 

 flower. The plants which bore these four distinct types of 

 blossoms could not be distinguished in the field by vegetative 

 characters, and the only obvious difference between the flowers 

 was in the color of the petals, which in all of the forms were 8-9 

 cm. long. Bailey* considers it probable that 77. oculiroseus is a 

 variety of 77. Moscheutos. The other types may possibly be 

 hybrids between the two more common forms which have been 

 given specific rank. 



The blossoms of hibiscus are among the largest in our native 

 flora, and for this reason their diurnal periodicity is very specta- 

 cular. If in the evening we mark in some fashion the largest 

 flower buds of one of these swamp hibisci, choosing only those of 

 which the convolute corolla projects beyond the partially opened 

 cal>'x, we shall find that most, if not all, of them will open on the 

 following morning. In mid August, by 7:30 or 8 A. M. they 

 have unfolded to practically their fullest extent. During the 



* Baile>-, L. H. Manual of Cultivated Plants. New York, 1924. 



