HYPOGYNOUS MONOCOTYLKDONS 



197 



being regarded as sepals, the inner ones as petals. These 

 two sets of organs constitute Xh&Jloral envelopes, and are 

 not essential parts of the flower, as it can fulfill its office 

 of producing fruit and seed without them. Note their 

 mode of attachment to the receptacle and how they alter- 

 nate with each other. 

 Remove one of the se- 

 pals and one of the 

 petals, and notice any 



372. — Vertical section of yucca whipplei : 



ped, peduncle ; br, bract ; r, receptacle ; per, 



371. — External view of a yucca perianth; sta, stamen; 0, ovary: sty, style; 



blossom ; (5r, bract; /i/, peduncle; stg, stigma. The last three parts named 



/■, receptacle ; s, sepal ; pet, petal. compose the pistil. 



differences between them as to size, shape, or color. 

 Which is most like a foliage leaf .'' Hold each up to the 

 light and try to make out the veining. Is it the same as 

 that of the foliage leaves } How many of each are there .■" 



283. The Essential Organs. — Next sketch the flower on 

 its inner face, labeling the six appendages just within the 

 petals, stamens, and the central organ within the ring of 

 stamens, pistil. These are called essential organs because 

 they are necessary to the production of fruit and seed. 

 Note their mode of insertion, three of the stamens alter- 

 nating with the petals and the other three with these, and 

 with the lobes of the base of the pistil. 



284. The Stamens. — Notice whether the stamens are 

 all alike, or whether there are differences as to size, 

 height, shape, color, etc. Do these differences, if there 

 are any, occur indiscriminately and without order, or in 

 regular succession between the alternating stamens .' Ex- 

 amine one of the little powdery yellow bodies at the tip 



