A LOXG-STALKED ELODEA FLOWER 49 



It seems to differ markedly from described North American 

 species in the possession of this long peduncled starainate flower. 

 But as this axis does not elongate conspicuously until a few hours 

 before the flower opens, the suggestion naturally arises that it 

 may have been overlooked elsewhere and the description based on 

 immature material. Under this assumption one is lead to com- 

 pare it with Elodea Planchonii Casp. {Philotria PlancJionii 

 [Casp.] Rydb.) which is described as having a short pedicelled 

 staminate flower, but a comparison of these forms shows many 

 other points of difference. 



Elodea Planchonii Casp. Elodea ioensis 



Based on description of 

 Philotria Planchonii (Casp.) Rydb. 

 Leaves 7-15x1-2 mm. " Leaves 8-14x2-3.5 mm. 



Staminate flower short-pedicellecl. Stamiuate flowers long-pedicelled. 



-Pedicel . -Pedicel 5-25 cm. long. 



-Spathe peduncled. -Spathe sessile, contracted at 



base. 

 -Sepals elliptic, 5 mm. long. -Sepals oval, 4 mm. long. 



-Petals lacking. -Petals present, linear-lanceolate, 



long-acuminate, etc. 

 -Anthers 3-4 mm. long. -Anthers, 2.5-3 mm. long. 



Pistillate flower, tube 3-5 cm. long. Pistillate flower, tube 3-15 cm. long. 



-Sepals linear, 3 mm. long. -Sepals oval, 2 mm. long. 



-Petals linear, 3 mm. long. -Petals obovate, 2 mm. long. 



-Stamens none. -Sterile stamens, 3. 



Figs. 5 and 6 illustrate fundamental differences between the 

 staminate flower of this form and that of Elodea canadensis 

 ^lichx. at corresponding stages of development ; at any later 

 stage the contrasts would be more marked. ]\Iinor differences in 

 form of petals and sepals for both flowers occur, and of course 

 there can be no agreement with the hermaphrodite form of E. 

 canadensis Michx. 



Comparison with the South American species credited with 

 long stalked staminate flowers is difficult from the descriptions 

 since the same term "tubus calicis" is applied to the elongated 

 portions of both pistillate and staminate flowers, though it is 

 highly improbable that they are structurally identical. How- 

 ever, in summarizing the characters of Elodea chile nsis Casp. 

 Caspary^ says, ' ' ]\Iannliche Bliithe, wie die weibliche mit sehr 

 langer Rohre des Kelches, 8-48'^' lang. Die mannliche Bliithe 



= Loc. cit., p. 470. 



