INTRODUCTION XXVll 



or four petals placed crosswise, as in the Cruciferce {vide infra), and 

 the papilionaceous (Latin papi/io, a butterfly) characteristic of 

 the Pea and Bean tribe, in which there are five petals, the posterior 

 one — that nearest the stem — called the standard and usually the 

 largest, the two side ones termed wings, and the two lower or 

 anterior ones, often slightly united, known as the keel (p. 113). 



Among gamopetalous corollas the chief polysymmetric forms 

 are — . 



Tubular, narrow, as if formed by united erect petals, as in the 

 florets of Thistles or the disk-^orets of a Daisy. 



Bell-shaped, wider, as in Campanula (p. 299). 



Salver-shaped corolla of Cruciate corolla : c, gibbous calyx. 



Primrose. 



Urceolate, or barrel-shaped, as in Heaths (p. 307). 



Funnel-shaped, as in the Small Field Convolvulus. 



Trumpet-shaped, with reflexed margin, as in the Large White 

 Convolvulus. 



Salver-shaped, with long tube and limb at right angles to it, as 

 in the Primrose. 



Rotate, or wheel-shaped, with a short tube, as in Pimpernel, 

 Forget-me-not, and Elder. 



The chief monosymmetric gamopetalous types are the bi-labiate, 

 or two-lipped, and the ligulate, or strap-shaped. The bi-labiate 

 may be either ringent, or gaping, as in the Natural Order Labiate; 

 ox personate (from persona, a mask), as in Toad-flax. The ligulate 

 occurs in all the florets of the sub-order Liguliflorai in the Order 

 Composite, as in the Dandelion and Chicory, and in the outer or 

 ray florets of many other Composites, such as the Daisy. 



In some cases, such as the Flaxes, the corolla is fugacious, 

 falling off directly it is gathered ; and in a few others, as in 



