DEVELOPMENT OF FLORAL ENVELOPES. 185 



are to be referred to the row of the corolla or of the stamens. The 

 paraphyses of the Passion-flower, the crown of Narcissus, and the 

 coronet of Stapelia, are referred sometimes to the one and sometimes 

 to the other. In general, they may be said to belong to that series 

 with which they are immediately connected. Some have attempted 

 to give names according to the parts of which they are modifications, 

 by prefixing the term para (vet^ot, beside, or close to), and speaking 

 of paracorolla and parastemones. 



385. Petals are attached to the axis usually by a narrow base, but 

 occasionally the base is larger than the limb, as in the Orange flower. 

 When this attachment takes place by an articulation, the petals fall off 

 either immediately after expansion (caducous), or after fertilization 

 (deciduous). A corolla or petals which are continuous with the axis 

 and not articulated, as Campanula, Heaths, &c., may be persistent, and 

 remain in a withered or marcescent state while the fruit is forming, 

 A gamopetalous corolla always falls off in one piece. Sometimes the 

 base of the corolla remains persistent, as in Ehinanthus and Oro- 

 banche. 



386. Development of Floral Envelopes. The floral envelopes, when 

 monosepalous and monopetalous, first appear in the form of a ring, 

 whence various cellular projections arise, constituting the sepals and 

 petals ; when they are polysepalous and polypetalous, the ring is 

 wanting. Even when the parts become ultimately 



unequal, as in Digitalis (fig. 288), they form equal 

 cellular papilla? when first developed (fig. 305). 

 Barneoud has shown this in the irregular Ranun- 

 culaceaa, Violacese, Orchidacese, Labiatae, Scrophu- 

 lariacea?, Leguminosae, and Polygalaceae. 



387. In Begoniacese, the floral envelope at first 

 appears as a continuous ring, having five very equal 

 small segments ; some of these, especially in the 



male flowers, disappear entirely or become atrophied. All the obser- 

 vations of Barneoud confirm Decandolle's statement, that irregular 

 flowers are to be referred to regular types, from which they seem to 

 have degenerated. There appear to be three principal kinds of irre- 

 gularity among corollas : 1. Irregularity by simple inequality of 

 development of the several segments, often along with adhesion or 

 atrophy, or arrest of growth : this is the most common kind. 2. Irre- 

 gularity of deviation, when the segments, though equal, turn all to 

 the same side, as in ligulate florets. 3. Irregularity by simple meta- 

 morphosis of stamina, as in Canna. The irregular corollas of Acan- 

 thacese, Bignoniaceas, Gesneracese, Lobeliaceae, and Scrophulariaceae, are 

 formed at first in a regular manner by equal projections from a sort of 



Fig. 305. Bud of the irregular gamopetalous flower of Digitalis purpurea. c c, Calyx, p. Corolla, 

 which in its early development is regular. , The stamens at first projecting beyond the corolla. 



