FLORAL ENVELOPES. CALYX. 



173 



360. The nature of the hairs on the calyx gives rise to terms simi- 

 lar to those already mentioned as applied to the surfaces of plants 

 (^[ 60). The vascular bundles 



sometimes form a prominent rib 

 (figs. 272, 273), which indi- 

 cates the middle of the sepal, at 

 other times they form several (fig. 

 274). The venation is useful in 

 pointing out the number of leaves 

 which form a gamosepalous calyx. 

 At the part where two sepals 

 unite, there is occasionally a pro- 

 minent line, formed by the union 

 of the vessels of each (fig. 274), which divides near the apex into two 

 branches, each following the course of their respective sepals. 



361. In a polysepalous calyx, the number of the parts is marked by 

 Greek numerals prefixed. Thus, a trisepalons calyx has three sepals, 

 pentasepalous or pentaphyllous, five, as in Stellaria Holostea (fig. 269), 

 and so on. The sepals occasionally are of different forms and sizes. 

 Thus, in Aconite, one of them has a peculiar helmet shape, and has 

 been called galeate (galea, a helmet); some authors regard this as a 

 petal, but it seems to belong to the outer whorl, and is consequently 

 a part of the calyx. In Calcophyllum, one of the sepals enlarges after 

 the corolla falls, and becomes of a fine pink colour. 



362. In a monophyllous or gamosepalous calyx, the sepals adhere 

 in various ways, sometimes very slightly, as in CEnothera; and their 

 number is marked by the divisions at the apex. These divisions are 

 either simple projections in the form of acute or obtuse teeth (fig. 273), 

 or they extend about hah way, as fissures, the calyx being trifid (three- 

 cleft), quinquefid (five-cleft), as in Primula elatior (fig. 272), according 

 to circumstances; or they reach to near the base in the form of parti- 

 tions, the calyx being tripartite, quadripartite, quinquepartite, &c. The 

 adhesion or union of the parts may be complete, and the calyx may 

 be quite entire or truncate, as, in some Correas, the venation being 

 the chief indication of the different parts. The adhesion is sometimes 

 irregular, some parts uniting to a greater extent than others, thus 

 forming a two-lipped or labiate calyx, which, when the upper lip is 

 arched, becomes ringent. The upper lip is often composed of three 

 parts, which are thus posterior or next the axis, while the lower has 

 two, which are anterior. The part formed by the union of the sepals 

 is called the tube of the calyx; the upper portion where the sepals 

 are free is the limb. Sometimes a monophyllous calyx assumes an 



Fig. 279. Quinquefid or five-cleft calyx of Primula elatior or the oxlip. 



Fig. -/7o. Five-toothed calyx of Silene inflata. 



Fig. 274. Calyx, c, of Hibiscus, with its caliculus or epicalyx, b. 



