376 



POLYGALACE^E. 



[Hypogynous Exogens. 



Milkworts are remarkable, among other things, for the irregularity of their flowers 

 which is such as to obscure, in a great measure, the relative position of the sepals and 

 petals The calyx apparently consists of but three pieces, which are usually green and 

 like sepals in their common state ; but their real number is 5, the two co oured la eral 

 petal-like bodies sometimes lying within the apparent sepals being in reality part , ofthe 

 series of the calyx. The corolla is mostly monopetalous, and, if carefully examined formed 

 of 3 pieces ; namely, the keel and two petals, all blended together. We have, therefore, 

 an abortion of two petals, according to the laws of alternation Bn this is not all; 

 there is not only an abortion of two petals, but of those two which would, if present be 

 found right and left of the keel. The monopetalous corolla is, therefore, formed by the 

 cohesion of the two posterior and the anterior petal of a pentapetalous corolla, of which 

 the two lateral petals are suppressed. The keel has an appendage of an anomalous 

 character, called technically a crest, and often consisting of one or even two rows of 

 fringes or divisions, originating not from the margin but from withm it and sometimes 

 cohering in a common membrane at their base. Aug. de St. Hilaire has shown tha. 

 this crest is nothing more than the deeply-lobed middle segment of a keel, with these 

 lobes in such a state of cohesion that the central lobe is pushed outwards, white the 

 lateral ones cohere by their own margins and with its back. The stamens are only 8 . 

 two therefoi^ Tare suppressed, lite relative position of the fifth sepal and petal res- 

 nectivelv, was first indicated by Brown. 



Milkworts are stationed by De Candolle between Sundews and Poreworts (Treman- 

 drace*), and in the immediate vicinity of Violetworts. With the latter they were 

 thought to be related on account of their hypogynous stamens, irregular flowers, and 

 cucuflate stigma; and with Poreworts on account of the caruncula of their seed, lo 

 Fumeworts they approach in the general aspect of their flowers, and in htt e more. 

 Leguminous plants are, notwithstanding their perigynous stamens, an Order with which 

 Milkworts seem at first sight to have some affinity ; the irregularity of corolla is ot a 

 similar nature in both ; there is in Leguminous plants a tendency to suppress the upper 

 lateral petals in Erythrina, as in Polygala, and the ascending direction of the style with 

 a cohesion of stamens are characters common to both Orders. Many additional obser- 

 vations are made to the same effect by St. Hilaire and Moquin-Tandon, who, moreover 

 compare the Order with Rueworts ; but those authors appear to have finally decided 

 upon the true position of Milkworts being in the vicinity of Soapworts ; remarking that 

 "the calyx of the latter is unequal, the corolla very irregular, and the ovary of Schmide ha 

 usually 2-celled and 2-seeded, like that of Polygala. Moreover, a great part ot the 

 genera of that Order have, with a calyx of five divisions, a corolla with four petals, and 

 the place of the fifth is manifestly vacant. This suppression is not exactly the same as 

 what is observed in the corolla of Polygala, where there are only 3 petals with 5 sepals ; 

 but the suppression has more analogy with what concerns the stamens, since with a 

 quinary number in the calyx each Order has eight antheriferous filaments. In this 

 H J view I fully agree. The unsym- 



metrical flowers, more especially 

 manifested in the reduction of the 

 number of carpels to 2 or 3 in a 

 structure otherwise quinary, the 

 definite ovules, the twining habit of 

 Comesperma,the samaroid fruit of 

 Securidaca, and it may even be 

 added, the deleterious qualities of 

 some Polygalas, together with the 

 saponaceous secretions of the 

 Monninas, are all arguments of 

 the strongest kind in favour of 

 Milkworts and Soapworts belong- 

 ing to the same Alliance. 



Certain anomalous genera, be- 

 longing as I think to this Order, 

 have been elevated to the rank of 

 Natural Orders. Of these Trigo- 

 nia, a genus of tropical American 

 trees, has been divided from 

 Milkworts because of its leaves 

 being opposite and having sti- 



Fig. CCLXIII. 



Fie CCLXIII.-Trigonia crotonoides.-^. de St. Hilaire. 1. a flower seen from the side ; 2 the 

 corolla, wUh the petals displayed in their natural position; 3. a pistil; 4. cross sect.on of the ovarj , 

 5. cross section of a seed. 





