78 The Waterlilies. 



(A 7 ", ampla) to pink (N. versicolor) and royal blue (N. zanzibariensis) 

 in Apocarpiae. In Hydrocallis a creamy white prevails. Orange tints 

 have been obtained in hybrids of N. flava and alba rubra (JV. aurora, 

 seignoreti). In size, N. tetragona, fennica, and odorata minor stand at one 

 end of the line, with flowers 3.5 to 5 cm. across, and at the other end are 

 A^. rubra, dentata, zanzibariensis, and giganlea, whose flowers measure 

 30 cm. or more in diameter. There is, of course, great variation within 

 a single species, according to the food supply and other conditions. Other 

 general characters will be brought out in the following description of the 

 flower and flower-stalk. 



So close is the resemblance between petiole and peduncle in Nym- 

 phaea that we shall greatly abbreviate the present section by referring 

 back to the previous one. The peduncles are always terete, and in color 

 and presence or absence of pubescence are like the petioles of the same 

 species (no brown stripes occur on the peduncles of N. tuberosa). In 

 Eu-castalia the likeness extends to the length, diameter, and number of 

 air-canals of the two organs. In Chamaenymphaea the likeness includes 

 length and diameter. The same is true of Xanthantha when in deep 

 water ; in shallow water, the peduncles are stouter. These species are also 

 peculiar in that the upper part of the flower-stalk is somewhat four- 

 furrowed with shallow rounded grooves. In all other species the 

 peduncles are 1 to 2.5 cm. in diameter, and stiff enough to raise the 

 massive flowers 5 to 30 or 40 cm. above the water. The more slender 

 peduncles of N. amazonum (Hydrocallis) are yet quite stiff and reach to 

 or very little above the water surface. In exceptionally shallow water the 

 same may be true for all of the Castalia group. 



The epidermis presents nothing characteristic. It bears a large num- 

 ber of hair bases. Beneath it there is a single layer of thin-walled cells in 

 N. dentata, rubra rosea, devoniensis, amoldiana, and zanzibariensis. The 

 inner wall of this layer is somewhat collenchymatous in N. zanzibariensis X , 

 marliacea chromatella, alba candidissima, and gladstoniana. Following this 

 layer in the above-named forms, or including it in N. rubra, lotus, slurle- 

 vantii, caerulea, odorata, and tuberosa, there are 3 to 1 1 layers of collen- 

 chyma as in the petiole. The character of the remaining tissue is also 

 like that of the petioles. In Apocarpiae the cells contain a good deal of 

 starch, but not so in Lotos and Eu-castalia. Four main air-canals 

 traverse the peduncles of Castalia, but six is the standard number for the 

 remaining groups ; these numbers are subject to an occasional variation 

 of one more or less, but much oftener of one more. The canals are equal 



