120 



1912, /. Limell (Cotype) (NY). Nebraska: On Middle Loup 

 River, near Thedford, Thomas Co., Aug. 7, 1893, P. A. Rydberg, 

 no. 1609 (NY) ; on South Fork of Dismal River, Aug. 12, 1893, 

 P. A. Rydberg, no. 1609 [ !] (US) ; on Middle Loup River, near 

 Mullen, Hooker Co., Aug. 19, 1893, P. A. Rydberg, no. 1609 [ !] 

 (US) ; South Cody Lake, Sept. 19, 1915, Ray Thomson (US). 



Division of Plant Exploration and Introduction, 

 Bureau of Plant Industry, 

 U. S. Department of Agriculture, 

 Washington, D. C. 



Marine Flowering Plants 



Harold N. Moldenke 



It is, of course, well known that there are a great many genera 

 and species of flowering plants which are not only able to live under 

 very saline conditions along the sea-coasts of the earth and at the 

 borders of salt lakes, but many which in fact thrive only in such 

 situations and under such conditions and will not grow well, if at 

 all, in any other habitat. Such plants are known as halophytes. 

 Many scores of species of flowering plants grow regularly on land 

 which is periodically inundated by rising tides of salt water (as, for 

 example, Eriocaulon parkeri), while the value of mangroves 

 {Avicennia, Rhisophora, Laguncularia) in extending the margin of 

 land into the sea in the famous mangrove-lagoons of tropical 

 regions is well known. 



These plants, however, are all fundamentally terrestrial plants. 

 It is not so well known by the general public or even by botanical 

 students that a considerable number of genera and species of 

 flowering plants actually are able and do live all of their lives in the 

 sea, completely submerged at all times by the water of the earth's 

 oceans, in company with the many thousands of microscopic and 

 macroscopic species of blue-green, green, red, and brown algae, 

 which are the true "seaweeds" as we usually think of them and 

 which are flowerless and much more primitive types of plant life. 

 The marine flowering plants often grow in colonies fully as exten- 

 sive as those of some marine algae and are, in fact, often mistaken 



