218 



ORGANOGEAPHY. 



observer to recognise the primary froiu the secondary divisions. 

 When a monosepalous calyx is entire, the number of sepals 

 can then only be ascertained by the venation, as the principal 

 veins from which the others diverge generally correspond to 

 the midribs of the component sepals. In a monosepalous calyx 

 in which the union exists to some extent, the part where the 

 sepals are united is called the tube, the free portion, the limb, 

 and the orifice of the tube, the throat ot faux {figs. 444 and 445). 

 If the union between the sepals is unequal, or the parts are of 

 different sizes, or of irregular form, the calyx is said to be irre- 

 gular {fig. 445) ; if, on the contrary, the parts are alike in form, 



of the same size, and united 



Fig. 444. 



Fig. 445. 



so as to form a symmetrical 

 body, it is regular {fig. 444). 

 Some forms of the irregular 

 and regular calyx have re- 

 ceived special names. Thus 

 in the Dead-nettle {Lamium) 

 {fig. 445), the irregular calyx 

 is said to be bilabiate or two- 

 lifped, because the five sepals 

 of which it is composed are 

 united in such a manner 

 as to form two lips. Of the 

 regular forms of the mono- 

 sepalous calyx a number 

 are distinguished under the 

 names of tubular, bell-shaped or campanulate, urceolate or 'pitcher- 

 shaped {fig. 444), conical, globose, &c. The application of these 



Fig. AAA. Urceolate calyx of Henbane 

 (Hyoi^cyamiLft). — Fig. 445. Bilahiate 

 calyjc of tiie Dead-nettle {.Lamium). 



Fig. 446. 



Fig. 446. Vertical section of the flower of the 

 Myrtle (Myrtus communis), cal. Tube of the 

 calyx adherent to the ovary o. 3. Stamens. 



will be shown when 

 speaking of the corol- 

 la, in which similar 

 forms occur, and in 

 which they are usually 

 more evident. 



The tube of a mo- 

 nosepalous calyx or pe- 

 rianth sometimes ad- 

 heres more or loss to 

 the ovary, as in the Iris, 

 Gooseberry, Currant, 

 Myrtle {fig. 446), in all 

 the plants of the order 

 Compositae, and in those 

 allied to it {figs. 447, 

 448, and 449), and in 

 numerous other plants. 

 When this takes place. 



