376 NATURAL HISTORY OF PLANTS. 



The disk lining tlie receptacle is sometimes thin and inconspicuous ; 

 again, the glands, into wliich, as we have seen, its edge is split, may 

 become very prominent ; they may be quite free or united in pairs. 

 This disk usually stops abruptly below the insertion of the stamens ; 

 but in several herbaceous species the stamens are inserted, not only 

 within its edy:es, but all over its surface, rii^ht down from the base of 

 the perianth to near the insertion of the gyna3ceum.' The number 

 and position of the carpels are very variable ; they may be equal in 

 number to the petals and superposed to them, as above ; or double 

 their number, half being superposed to the sepals.* But, strange to 

 say, those in front of the petals may then disappear, leaving only 

 those superposed to the sepals.' Finally, their number may be in- 

 definite, or it may diminish to less than four or five, and even be 

 reduced to one or two.' Rarely are the carpels not quite free from 

 each other, and sometimes the organic apex of the receptacle will even 

 rise up into a little cone and separate the ovaries,* But sometimes 

 the latter are all united for a variable height, so that a transverse 

 section of the lower part of the gyna^ceum will show a single several- 

 celled ovary with axile placentation.** The ovules are not invariably 

 indefinite, and horizontal or only slightly descending. There are 

 sometimes only two, or even a single one," descending and completely 

 or nearly anatropous, with the micro pyle upwards and outwards. 



any case so ill-nmrkcd that it is not worth while pendula. S. lobata has often eight or nine 



to take it into consideration. The floral hracts carpels, with a tetramerous perianth, 



are here carried up very high on their axillary ' In S. Lhtdlcyana, for instance, as pointed 



pedicels. out hy Kckpek. This also occurs in S. sorLi- 



' Thus, in S. lobata the stamens are inserted folia, the t\pe of the section Surbaria (Skk., 



as alwve, over the whole surface of the recep- loc. pit., 545), or iSchizunotus (Lindl., tt'all. 



tacular disk. In S. Ulmaria, Vauchek has de- Cat., n. 703). 



nied the existence of a disk, and supposed that * As in «S'. Aruncus, the type of the section 



the stamens were liypogynous. Hut they are ^4rw«c««(SEn., /or. cj7., 515), which, iiowever, has 



inserted on the periphery of the receptaculiir more frequently three or four ; also in the allied 



sac, and tliere is a yellowish disk with its frillid species, which arc most prohahly only forms of this, 



edge just internal to their insertion. In S. Fili- These jjlants have usually unisexual tlowcrs. 



fendula the stamens are placed at dillerent * This is pretty well marked in A'. i'(Vi/>fi»</«/a, 



heights on the inner surface of the receptacle. dtciimbtns, &c. 



But the outermost are inserted a good way below * The hj)ecie8 where this union takes place to 



the petals. The latter have articulated basis each its fullest extent is .V. /,(«</ /rv««(i, whose ovary 



Heated just in tiie Ixtttom of tiie sinus between in tiiis respwt recalls that of VauqutHnia, while 



two adjacent sepals. The shallow receptacle of its car|H>ls are also alternipettilous ; so that N. 



«S'. Arurn-UM is lined by a glandular disk, whoso Liinllei/ana links Vauqueliuia and Sftirna. 



edges are indistinctly lobed ; but there are none More frequently the carpels tif the latter genus are 



of the proiiiininl isolated or geminato nuirginal onl\ united for a very little way above the has*', 



glands found in most of the other species. In ^ There are usually only two in N. Filipm- 



,V.*oW/i/o/i« the margins of the iiitra-reciiitacular </(//<i, and tiny become almost sujicrjH)M-«i. >'. 



glandidiir layer are nearly entire, as they often JninrtiJt, litvii/atn, Ac, have often two pairs of 



are in Kriogijna. descending ovules. A. lobntu has tuo i,viile>. or 



■■' There are as many as liftcen in S. Fili- more rarely a single one. 



