inferior Paleee of the Grasses. 177 



still pass immediately into each other (fig. 6 — 8). The ligula is 

 formed by the elevation of a transparent scale on the upper sur- 

 face of the leaf in a transverse or somewhat oblique direction. 

 Very frequently it is developed only on the central portion of 

 the leaf, and has then usually a crescent shape (fig. 7) ; in other 

 cases this incipient ligula is only met with on one of the sides of 

 the leaf (figs. 6, 8) ; very frequently it docs not extend to the 

 margin of the leaf, and every trace of its auricle is still wanting 

 (figs. 7, 8) ; in other cases the auricle is developed without the 

 central portion of the ligula being present. The development of 

 the auricle takes place in the following manner : the scarious 

 margin of the leaflet, which extends at a less advanced stage of 

 transformation to its apex, retracts itself as it were from above 

 downwards, and instead of gradually becoming acute and dis- 

 appearing in the green-coloured margin of the leaf (fig. 6), now 

 projects in the form of a rounded prominence on the margin of 

 the leaflet, and passes into a scale projecting on the upper sur- 

 face of the leaflet (fig. 6 a) . In this manner the ligula appears, 

 not as a part foreign to the leaf and adnate with it, but as an ex- 

 uberant growth from it like the corona of the petals of a pink. 

 Simultaneously with the perfect development of the ligula occurs 

 the formation of the node between the vagina and lamina, and 

 thereby a distinct separation of the two parts of the leaf. 



Far more important is the consideration of the base of the 

 metamorphosed palese, as regards the question which principally 

 occupies our attention. While the base of the normal palea al- 

 ways surrounds only a portion of the axis, and consequently leaves 

 it doubtful whether the palea is the product of the primary axis 

 of the gramineous flower, or whether it forms a verticil with the 

 two leaves composing the superior palea, not the least doubt can 

 exist respecting this point in the metamorphosed palea ; for not 

 only does its base surround the stem entirely, but both its mar- 

 gins cohere towards its lower extremity (fig. 5 p') . Now it is 

 perfectly evident in this case, that the axis which is surrounded 

 by the leaflet, and from which this takes its origin, is the pri- 

 mary axis of the spicula, and that the superior palea belongs to 

 the floral axis, situated in the axis of the inferior palea ; conse- 

 quently that the inferior palea must not be considered as a peri- 

 gonial leaf, but as a bract. 



In proportion as the above-described metamorphosis of the 

 palea into a vegetative leaf advances, the flowering organs de- 

 crease in size. In the axis of the palea of the lowest flower of a 

 spicula, we generally find the whole of the floral parts in a crip- 

 pled state ; the superior palea is generally still very large in com- 

 parison to the other flowering organs, and bifurcate at the apex, 

 but not separated into two distinct leaflets. In the axis of the 



Ann, S^ Mag. N, Hist. Vol.xv. 



