NECTARY. 49 



4. Caryophyllaceous, like the piiik. This corolla consists of 

 five petals, having long claws immersed in a tubular calyx. Ex. 

 pink, cockle (Fig. 4). 



5. Papilionaceous y butterfly-shaped. Tliis corolla consists of 

 five dissimilar petals, which have received names as follows ; — 

 the upper and largest is called the banner {vexillum) ; the two 

 lateral ones beneath this, the wings (alee) ; and the two lower 

 ones cohering by their lower margins, the keel (carina). Exam- 

 ples, pea, bean, locust. Plants with this kind of corolla consti- 

 tute the greater part of the Leguminosse, one of the most 

 extensive and useful of the natural famihes. 



106. Physiological structure. The floral envelopes are 

 found, in their physical organization, to agree with leaves, of 

 which they are only modifications. They consist of thin expan- 

 sions of cellular tissue, traversed by veins of dehcate spiral 

 vessels, all covered with an epidermis often having stomata. 

 Their various colors are produced by secretions contained in the 

 little bladders of the cellular tissue. 



§ 7. OF THE NECTARY AND DISK. 



107. These are terms which have been apphed to certain 

 anomalous forms of the floral organs, and are very variable in 

 structure and position. 



a. The nectary (nectar, honey) is properly an apparatus for the secretion of 

 honey. In the violet, larkspur, columbine, &c., it consists of a prolongation of 

 the petal into a spur. In the nasturtium it is a similar prolongation of the sepal. 

 In the passion flower, grass parnassus, gold-thread, &c., the nectaries are merely 

 abortive stamens passing into petals. In the lady's slipper and other Orchida- 

 ceous plants, the lower petal being inflated and larger than the rest of them, was 

 called nectary by the Linnean school, but by modern writers the labellum, or 

 lip. 



b. The DISK is a term applied to certain little projections situated between the 

 bases of the stamens and the pistils. Its more common form is that of a raised 

 rim, cither entire or variously lobcd, surrounding the base of the ovaiy, that is, 

 hypogynous {HittZ, under, ywii, the pistil), as in the peony, or it appears at the top 

 of the ovary when the calyx is superior, and is then said to be cpigynoiis (kt/, 

 upon, yuvn), as in the Comus. 



c. The true character of the disk is little understood. It is supposed by 

 Llndley to consist of stamens in a rudimentary state, as it is sometimes separated 

 into a circle of glandular bodies, alternating with the tnie stamen^!. 



