BRACTS AND FLORAL LEAVES. 85 



upon simply as the free lobes of the calyx. In a perigynous 

 flower, therefore, the petals and stamens were regarded as 

 adherent to the calyx. The union between the hollow receptacle 

 and the gyncecium (p. 81) in an epigynous flower was similarly 

 taken to be an adhesion between "calyx tube" and gyncecium. 

 In this case the calyx was termed "superior," because its 

 " lobes " had a position obviously above the adhering part of 

 the gyncecium. In other cases it was called " inferior." 



External Characters. — The calyx may be radially or bilaterally 

 symmetrical. When polysepalous, the individual sepals can be 

 described in the terms used for foliage leaves. They are never 

 stalked, but may possess stipules at their points of attachment 

 These, if large, look like an outer whorl of sepals, which receives 

 the name epicaly.c, as in strawberry and marsh-mallow. An epi- 

 calyx may also be formed by bracteoles. The sepals are some- 

 times divergent or spreading, as in the tallest form of buttercup 

 (Ranunculus acris), or again they may be reflexed, i.e., bent back, 

 of which another common kind of buttercup {Ranunculus bulbosus) 

 is an example. Sepals are frequently more or less swollen or 

 saccate at their base. This is the case with the two lateral sepals 

 of wallflower and shepherd's purse. Such a swelling may be 

 exaggerated into a tubular structure termed a spur, which is then 

 usually a nectary, secreting honey on its inner surface. In the 

 buttercup, as we have seen (p. 74), the nectaries form part of the 

 petal, and indeed these organs vary very much in position accord- 

 ing to the kind of plant examined. In some cases they are found 

 away from the flower altogether. Examine the bilaterally sym- 

 metrical calyx of a pelargonium, first removing the petals. Five 

 sepals will be seen, a large pair on the anterior side, then a 

 smaller pair, and lastly, a much larger unpaired posterior one. 

 By looking clown upon the calyx a small hole will be seen be- 

 tween the odd sepal and the pink structures in the centre of the 

 flower. A needle pushed into this will enter a short tube which 

 can be seen as a ridge on the outside of the flower- stalk. A 

 transverse section at this point will show both tube and stalk. 

 We have here a sp)ur, belonging to the posterior sepal, and firmly 

 adherent to the flower-stalk. A spur, however, is not always a 

 nectary. In the larkspur there are five large blue sepals, the 

 posterior one of which is produced into a large spur. This 

 simply serves as a cover to two small spurred petals, parts of 

 which, together with two small unspurred petals, are seen in the 

 centre of the flower. Monkshood is somewhat similar. The 

 "hood" formed by the posterior sepal encloses two small petals 

 (here the only ones), which are entirely changed into nectaries. 



When the calyx is gamosepalous the united part forms a tube 



