THE FLORAL ENVELOPES PERIANTH. 



115 



Fig. 207. 



calyx and corolla, as in the Tulip ; or of one circle, then always 

 called a calyx whatever its colour, as in Monochlamydeous flowers. 



A large numher of the Monocotyledonous orders 

 possess a petaloid perianth ; that is, there are two 

 circles of petaloid organs, which, from their resem- 

 blance, or actual coherence, have the appearance of a 

 single hexamerous whorl. This perianth may be re- 

 gular (fig. 207) or irregular, like the normal calyx 

 and corolla ; it may be polyphyllous or gamophyllous ; 

 and the outer circle may differ to some extent from 

 the inner in form, size, and colour, without other ir- 

 regularity. The forms are described by the same Regular e-merous peta- 

 terms as those used for the calyx and corolla E^SfagStg 



We have a regular polyphyllous perianth in the pogynous stamens and 

 Tulip and Lily ; a regular gamophyllous perianth in a - < Jj[ l jjJ]^k^J^ 

 Hemerocallis, Convallaria, Tarnus, &c. ; a regular poly- 

 phyllous perianth with unlike circles in Iris j and irregular polyphyllous 

 perianths in Zingiberaceae, Orchidacese, &c. 



Perianth of Orchids. The irregular perianth of Orchidaceae (figs. 

 208 & 209) requires especial mention, as the Order is very large and the 

 characters of the perianth peculiar. There are three outer organs (a, a, a), 

 more or less alike, and usually smaller than the inner; of the inner, the 

 lateral (b, b) are smaller than the posterior (6 f ), called the lip (or label- 

 lum), which is often excessively developed, and even divided into regions 

 which receive separate names ; in many of our native Orchids it possesses 

 a spur (fig. 208, &*). 



Fig. 209. 



Fig. 208. 



Fig. 210. 



Fig. 208. Flower of an 



Orchis, seen in its natural position, where, owing to the twisting of 

 the inferior ovary, the anterior or inferior part is above and the posterior below. 



, 



, a, a, represent the outer parts of the perianth or petals ; 6, 6, the lateral petals ; 

 b', the labellum, prolonged behind at the base into a spur, 6*. 

 Fig. 209. Ground-plan of the flower, with the same references. 



Fig. 210. Flower of Luzula: b, the 6-merous scaly perianth, surrounding six hypogyuoua 

 stamens and a central 3-cornered pistil with a single style and three stigmaa. 



i2 



