THE FLORAL SHOOT. 423 



certain familiar objects, names are often used which relate to 

 these objects. 



Flowers are said to be regular, or irregular. In a regular 

 flower all of the parts of a set or series are of the same shape and 

 size, while in irregular flowers the parts are of a different shape 

 or size in some of the sets. The flowers of the pea family (Papi- 

 lionacece), of the mint family (Labiatce), of the morning glory, 

 larkspur, monkshood, etc., are irregular (fig. 450). The corolla 

 usually gives the characteristic form to the flower, and the name 

 is usually applied to the form of the corolla. 



Some of the different forms are wheel-shaped or rotate corolla 

 when the petals spread out at once like the spokes of a wheel, as 

 in the potato, tomato, or bittersweet; salver-shaped when the 



Fig. 450. 



Several forms of flowers. Regular flowers, wh, wheel-shaped corolla; sa, 

 salver-shaped; tub, tubular-shaped. Irregular flowers, pa, butterfly or papilio- 

 naceous; per, personate or masked flower; lab, gaping or ringent corolla. The 

 two latter are called bilabiate flowers. 



petals spread out at right angles from the end of a corolla tube, 

 as in the phlox; bell-shaped, or campanulate, as in the harebell 

 or campanula; funnel-shaped, as in the morning glory; tubular, 

 when the ends of the petals spread but little or none from the 

 end of the corolla tube, as in the turnip flower or in the disk 

 florets of the composites. The butterfly, or papilionaceous cor- 

 olla is peculiar as in the pea or bean. The upper petal is the 

 "banner," the two lateral ones the "wings," and the two lower 

 the "keel." 



The labiate corolla is charcteristic of the mint family where 

 the gamosepalous corolla is unequally divided, so that the two 



