LDLIALES 441 



verse in combinations of primitive and advanced characters. Its various 

 genera show stages in the change from spiral to whorled arrangement 

 of the floral organs; in the reduction of the receptacle tips and the 

 carpellary stipes; in the occasional presence of more than six (nine to 

 twelve) stamens; in the connation of the carpels, laterally and ventrally; 

 and in the closure of the carpels. The origin and elaboration of the septal 

 nectary is well shown. 



The Liliaceae, as a whole, show steps in the union of the three styles 

 and stigmas to form a single, simple, median structure. No genus shows 

 all the more primitive characters; Veratmm and Tofieldm probably best 

 show general primitive structure. In Veratrum, the "whorls" of all floral 

 organs are shown by anatomy to be "tight" spirals, and there is a vestig- 

 ial receptacular tip between the carpels. The carpels are incompletely 

 connate; their distal parts are free and divergent. The carpel margins 

 are merely appressed, not histologically fused; the styles are structurally 

 unspecialized, resembling the fertile part of the carpel in shape, and 

 are open — horseshoe-shaped in cross section — distally. The three traces 

 of the carpels arise independently from the receptacular stele — in con- 

 trast with those of most higher taxa in the family, where they arise 

 fused. In advanced characters, the flower shows slight perigyny — the 

 stamens and perianth are adnate to the carpel bases. 



Primitive characters are seen in Toficldia; there may be 9 to 12 

 stamens, and the carpels, varying from three to five, are stipitate and 

 free of connation for some distance from the base, though often united 

 distally. In T. ghitinosa, the carpels are almost free of lateral connation. 

 There is no perigyny. In advanced characters, the flower of Tofieldia 

 shows appendages whorled, the receptacle not prolonged, and carpels 

 with a single trace. 



Absence of septal glands — highly specialized structures — characterizes 

 the Melanthioideae, primitive members of the Liliaceae. (Tofieldia per- 

 haps shows an early stage in these glands, but the epithelial lining of 

 the intercarpellary spaces is unlike that of the glands of higher sub- 

 families. ) 



The gynoecia of the Melanthioideae have been considered to re- 

 semble those of Butomtis (Helobiales) and Scheuchzeria (Alismatales) 

 — part of the evidence that these taxa belong to the same ancestral 

 line. There is surely close resemblance in the carpels, but this re- 

 semblance may represent merely the same level of carpel evolution. The 

 sessile stigma of Scheuchzeria shows stages in the evolution of a style, 

 stages similar to those in the more primitive lilies. Fusion of the carpels 

 in the Melanthioideae is ontogenetic; that in the more advanced genus, 

 Trictjrtis, is congenital, as in most of the Liliaceae. In the primitive 

 Liliaceae, placentation also shows steps in evolutionary advance. The 



