TEEATOLOnY OP ORCHIDS. 4.3 



variations furnisli the botanist, whether he be physiologist or morphologist, 

 or both, with endless opportunities for study and unlimited sources of 

 wonder and admiration. vSo far as appearance goes the lip is in general 

 the main feature of the flower, being usually different from the other 

 five segments, causing the flower to be irregular or " zygomorphic " 

 in its construction ; but in some few instances the lip is scarcely, if 

 at all, different from the other segments* and the flower is then 

 regular or " actinomorphic." 



We may take such flowers to represent an approach to the primitive, 

 unmodified type of orchid structure. In the cases mentioned the 

 regularity of the lip is the normal or usual state of things, but 

 where it occurs, as it often does, in flowers that are habitually 

 irregular, then we have the condition known as regular peloria.* In 

 Dendrobium, Phaltenopsis, Ltelias and Cattleyas, for instance, the 

 prominently large lip is occasionally replaced by one of approximately 

 the same dimensions and form as in the other perianth segments, while 

 in other instances the spur or the prominent ridges and teeth of the 

 lip are altogether deficient (see Figs. 3 and 4). Such changes are 

 of interest in some instances as bridging over the interval between 

 two supposed genera; thus a flower of GijpripecUum caudatum with a 

 flat lip and other changes afforded evidence that Uropedium can hardly 

 be separated as a genus from Selenipedium (see Fig. 7).t In such 

 flowers the tendency is towards a greater simplicity of structure, 

 or in other words, specialisation has not been carried so far as 

 usual. Hence cases of regular [)eloria are considered as instances of 

 reversion to a primordial or ancestral state. Not infrequently the lip 

 is altogether wanting. | 



The opposite condition to regular peloria occurs when the characters 

 proper to the lip are manifested also in the other two petals. Here 

 the irregularity is intensified instead of diminished ; the case thus 

 becomes one of " irregular " peloria. A familiar illustration occurs in 

 the variety of Dendrohium nohile known as Coolisoni anion (see Fig. 5), 

 and cases of " trilabellia " as Reichenbach called them are not uncommon 

 in Lfdia purpurata, CaJanthe ve^Hta, Odonfoglossiim odoratum var. 



* Besides those mentioned in the text other instances are afforded by Dendrobium normale, 

 the genera Thelyinitra, Thelasis, Neuwiedia. An orchid with perfectly regular flowers is 

 figured by Lindley in the Botanical llegisl.cr of 1838, t. 60, uiuler the name of Paxtonia 

 rosea, but Reichenbach and following him Bentham refer it to Spathoylottis plicata as a 

 peloriate form of that .species. One thing is certain, it has never been seen in a living 

 state since it was first sent from Manila by Cuming to Messrs. Loddiges in 1837. — M, T. M. 



+ Another evidence, and a strong one too, of the same tendency was obtained by fertilising 

 C'ypripedium longifolium, Rchb. , with the jtollen of Uropedium Lindenii, Lindl. {C, caudatum 

 Lindenii, Veitch) ; the resulting progeny proved to be structurally identical with Cijpri2)edium 

 grandc, jireviously obtained from C. lomjifoUithi, fertilisetl with the pollen of C. caudatum. 

 The only discernible difference between the two is that the pouch of the labellum of the 

 first-named hybrid is longer than that of C. (jrandc. — A. H. K. 



+ Almost normally so in the lowermost, often the two lowermost flowers in the raceme 

 of Grammatophyllum FenzUanum var. Mcasuresianum. — A. H. K. 



