GROUP V. ANGIOSPERMJE. 445 



leaves ; thus in sDme Rosaceae (Poteatilla, Comarum, Geum, Al- 

 chemilla) the stipules of the sepals form a calyculus or epicalyx : 

 stipules are developed in connexion with the petals of some 

 Sapotacese (Dipholis, Mimusops) : and in connexion with the 

 stamens of Allium, Ornithogalum, some Zygophyllaceae, etc. 



The Phyllotaxy of the Floicer. The floral leaves, like the 

 foliage-leaves on the stem (see p. 10), are frequently arranged 

 spirally, (e.g. Calycanthus, Anemone, Trollius) when the flower is 

 acyclic. The most common divergence is f, but higher divergences 

 also occur, especially in the androecium, when numerous small 

 organs are inserted upon an expanded axis (e.g. Ranunculus). In 

 the spiral or acyclic flower there is either no well-marked dis- 

 tinction of the various series, that is, the members of the calyx, 

 corolla, and androecium, are connected by intermediate forms (e.g. 

 Nymphsea) ; or the various series are sharply defined, each series 

 taking up one or more turns of the spiral. 



In most cases the floral leaves are arranged in whorls, that is, 

 the flowers are cyclic. Cyclic flowers are connected by inter- 

 mediate forms with the acyclic, especially through pentamerous 

 forms. Thus some pentamerous flowers are hemicyclic, that is, 

 some of their floral leaves are arranged spirally, and the others in 

 whorls. Instances of a spiral perianth combined with cyclic 

 sporophylls are afforded by those flowers in which the members of 

 the perianth, calyx, or corolla are developed in f succession, and 

 the prefloration is quincuncial (see p. 43) ; the perianth is spiral 

 in the flowers of the Cannabinacese and Chenopodiacese ; the calyx 

 is spiral in the flowers of the Bindweed (Calystegia Septum), the 

 Rose, some Boraginacese (Cerinthe, Echium, etc.), Geraniacese, 

 Oxalidaceae, Linaceae, Caryophyllacese, and many other dicotyle- 

 donous orders ; both calyx and corolla are spiral in Camellia, 

 though the phyllotaxy is not -. In other cases, the sporophylls 

 are spirally arranged, whilst the perianth-leaves are cyclic. For 

 instance, in Magnolia, Ranunculus, and Helleborus, both stamens 

 and carpels are spirally arranged ; and in Delphinium and Acoui- 

 tum, the stamens only. 



Closely related to the foregoing cases of phyllotaxy occurring 

 in fact not only in flowers of closely allied species, but also in 

 flowers of the same species are certain of the typical forms of 

 cyclic arrangement in which each series (whether perianth, calyx, 

 corolla, or androecium), instead of consisting of five floral leaves, 

 taking up two turns of a spiral with a divergence of -* , consists of 



