332 MORPHOLOGY. 



More will be said respecting this structure when we come 

 to speak of the different kinds of floral envelopes. 



Merely a few points require special notice here, because the principal 

 facts are self-evident, as mere analogical application of what has been 

 explained of the foliar organ in general. 



In the first place, some further remarks are necessary on the dis- 

 tinction between perianth and involucre. Both are undoubtedly 

 foliar organs on the axis itself; each foliar organ may be adherent 

 at its borders or free ; both may be green, brightly coloured, tough 

 or delicate, like all foliar organs. The bracts may stand at various 

 distances from the so-called parts of the flower ; consequently, there is no 

 distinction to be made between a one-leaved perianth and a bract, if we 

 do not pay attention to the number of foliar organs arising on a level 

 (in one circle) on the floral axis. Thus, and so alone, we acquire a per- 

 fectly strict and easily-maintained distinction for scientific description, if 

 we only reckon anything as belonging to the floral envelopes when it 

 consists of at least two foliar organs situated on a level, and call 

 every other merely single foliar organ of the flower a bract. In this 

 way we have a bracteola urceolata in Humulus and Cannabis, whereby 

 in each case they are not so far removed, according to the usual mode of 

 judging, from the true Urticacece, from which they are not to be separated 

 at all, as when a perianthium is ascribed to them. The distinction 

 between Salicacece and Cupuliferce is easily described ; although these 

 plants are of very simple structure, they exhibit a manifest advance in 

 the perfection of the flower. In the Salicacece the flower possesses no 

 foliar organs ; the glandula hypogyna in Salix, the so-called perian- 

 thium of Populus, are, according to their development, merely discs 

 (axial organs). In the Cupuliferce a perfect superior perianth exists ; I 

 have not yet become acquainted with the development of the Betulacece. 

 This much is certain, the axils of the bracteal scales of the catkin do not 

 bear single flowers but inflorescences (capitula), which distinguishes 

 them widely from the Salicacece ; but observation of the development can 

 alone decide as to the import of the foliar organs which exist here. In the 

 female flowers they are apparently bracts (not bracteoles), in the, male of 

 Betula the same, but in Alnus perianthial leaves. In the Myricacece and 

 Casuarinacece distinct di-merous circles of floral envelopes occur. The 

 Piperacece, including Saururus * f have the so-called naked flowers 

 (without any envelopes) in the axils of bracts. Among the Monoco- 

 tyledons the Orontiacece have a distinct perianth. Among the Naiadece, 

 Aponogeton and Ouvirandra have some coloured organs on the flower, 

 the nature of which cannot be determined for want of investigation of 

 development ; the scales of Potamogeton are nothing more than a scale- 

 like crest on the connective of the anther. None of the others have any 

 envelopes ; in Zarnichellia the female flowers are enclosed by a single 

 delicate bract f (spatha hyalina). 



* The Sauruace<e, as I have elsewhere observed, are not a distinct family, but a 

 strange mixture of Monocotyledonous and Dicotyledonous plants, which has originated 

 from imperfect knowledge ; Aponogeton and Otivirandrn are true Naiadce ; Saururus is 

 only generically distinct from Piper and Peperomia ; Houttuynia I do not know, there- 

 fore I cannot say whether it alone will justify the establishment of a special family. 



f The same botanists, who would of course admit that we can only speak of an her- 

 maphrodite flower when stamens and germens are inclosed in one and the same set of 

 envelopes, write coolly, Zarnichellia : flos liermaphroditus ; stamen unicum stipuhe op- 

 pnsitum, germina quatuor perianthio inclusa. See Nees ab JCsenbeck, Genera Plantnrum 

 Flor. Germanice. 



