:26 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



Lastly, we note what is perhaps the portant to note whether the overlapping 

 most important, as it certainly is the most is from right to left, Dextrorse (Fig. 100), 



striking and interesting, of the corolla 

 appendages— namely, the Crown. The 

 crown Is an outgrowth, more or less mem- 

 branaceous, from the face of the corolla. 

 Its morphological nature is not under- 

 stood or agreed upon. It may be a mere 

 abnormal product of median chorisis, or it 

 may be the homologue of the ligule of 

 certain loaves, hereafter to be considered, 

 the latter being regarded as a normal and 

 morphologically distinct part. When it 

 develops from a petal with a distinct 

 narrowed basal portion, which may be 

 assumed to correspond to the petiole of 

 the formative leaf, it usually develops 

 from the point where this is joined to the 

 broader portion, or near it (Fig. 96, a). 

 The crown becomes very important in 

 classification in such families as Passi- 

 floraceae and Amaryllidaceae. A ring 



of intruded folds at the throat is often, 

 perhaps incorrectly, called a crown. 



The arrangement of the parts of the 

 perigone in the bud yields some of our 

 most important diagnostic characters as 

 distinguishing orders, sub-orders and 

 genera, and has been the subject of elab- 

 orate classification. The demands of phar- 

 macognosy, however, call for attention to 

 only the principal types of Praefioration or 

 Aestivation. The three principal types 

 depend upon the fact that the combined 

 breadth of all the parts of a perigone circle 

 must, (1) be insufficient to enclose the 

 bud, in which case open spaces must be 

 left between their margins (Reseda) or 

 the summit must be left uncovered (Pig. 

 S7), the form in either case being called 

 Open; (2) it must be exactly sufficient to 

 enclose it, the edges then meeting exactly, 

 with nothing to spare, and the form being 



-called Valvate (Fig. 102, the calyx); or (3) 



it must be excessive, in which the excess 

 /may be disposed of in one of several ways. 



In one, the parts after meeting squarely 

 rare uniformly turned straight outward 



<Fig. 98), the form being called Valvate 

 : Reduplicate. In another they are turned 

 : straight inward, the Valvate Induplicate 



form {¥ig, 99). They may even be rolled 



or the reverse, Sinistrorse (Fig. 101). 



Other details as to the precise mode of 

 overlapping are frequently worthy of note. 



In determining the form of praeflora- 

 tion, care must be taken to select a well 

 formed bud. The praefloration may be 

 mixed, as in Oenothera, where the parts 

 are valvate at the base and slightly im- 

 bricate or reduplicate at the immature 

 apex (Fig. 102). At the best, intermediate 

 and perplexing forms will be encountered. 

 Petals, sepals or stamens are occasionally 

 rolled vertically downwards from the 

 apex, this form being called Circinate. 

 Occasionally we find the petals folded and 

 doubled in an irregular manner, the Crum- 

 pled or Corrugated form of praefloration. 

 A number of terms are called for by the 

 peculiar conditions of the gamopetalous 

 form. Economy of space is here com- 

 monly secured by a longitudinal folding, 

 the Plaited form. Vertical shortening is 

 often secured by twisting, the Convolute 

 form. 



The duration of the perianth, especially 

 of the calyx, is frequently of considerable 

 importance from the standpoint of phar- 

 macognosy, although in general not so. 

 When a part falls away at, or very shortly 

 after, expansion, it is Caducous. When 

 lasting about a day, and then either fall- 

 ing or perishing upon the flower, it is Fu- 

 ;racious. When lasting longer than a day, 

 but falling soon after fertilization, it ia 

 Deciduous. When remaining and retain- 

 ing more or less of its normal appearance 

 for some time after fertilization, it is 

 Persistent. When so remaining, but in a 

 Withered condition, it is Marcescent. 

 These definitions assume that fertiliza- 

 tion takes place normally. If this be ar- 

 tificially prevented or deferred, the fresh- 

 ness of a corolla is often very greatly pro- 

 longed. (See Fertilization.) Important 

 facts relating to the Accrescent calyx of 

 the fruit will be presented when the latter 

 is discussed. 



Some very interesting facts concerning 

 characteristic movements of the corolla, 



inward, the Involute form; when lapping Its sleeping and awaking and other habits, 

 the one over the other they are Imbri- should be sought in general works on 

 ^ate (Fig. 102, the corolla). Here it is iin- botany. 



