94 PRINCIPLES OP PLANT-TEIIA'I'OI.OGV. 



In grasses, regarded as a whole, very great reduc- 

 tion in the pistil has occurred ; however, in OMandra 

 there are many carpels ; in Streptochseta and Bamlnisa 

 there are three, i. c equal in number to the components 

 of the remaining whorls. In most grasses there is a 

 single carpel, but with two stigmas. Celakovsky has 

 shown that this is a case of incomplete reduction from 

 two carpels to one, comparable to a double leaf. 

 Occasionally a reversion to the original three carpels 

 occurs in the flower, as in the case of Scliocnodorus 

 elatior mentioned by Nees. There are, however. 



Fig. 103. — Erica Tetralix (Cross-leared Heath). Transverse section 

 of fruit, showing one or two extra whorls of carpels. (After 

 Turpin.) 



several cases in which three stigmas make their ap- 

 pearance; a proof that the immediate ancestors had 

 three carpels. 



Schlechter and Fischer described a peloric flower 

 of the orchid Odontoghssum grande in which the gynoe- 

 ceum was perfect, there being three rostella and three 

 stigmas on the interior side of the column, whereas in 

 the normal flower of orchids there is only one rostel- 

 lum present, and at most two stigmas. No more perfect 

 peloric orchid-flower than this has ever been described 

 (see Plate XXXVII, fig. 6). 



A crocus-flower, exhibiting rhythmic alternation in 

 the numerical constitution of its whorls, had four 

 carpels (fig. 104). 



