334 EXPLANATION OF THE PLATES. 



Fig. 5. — A small aquatic plant called JLwlwort (Subularia aqua- 

 tica), indigenous to the alpine lakes of Europe, and also to the 

 ponds of Maine. The leaves linear, subulate, and verticillat- 

 ed. a. The silicle, or short pod, of an oval figure, b. The 

 dissepiment and concave valves. 



Fig. 6. — The irregular cross-shaped flower of the Candytuft (Ibe- 

 ris umbellata), in which 2 of the external petals are enlarged. 



Fig. 7. — The open silicle of the Shepherd's-purse ( Thlaspi Bur- 

 sa-pastoris). 



Fig. 8. — The unopen, triangularly obcordate silicle. 

 PLATE III. 



PAPILIONACEOUS OR LEGUMINOUS PLANTS. 



A small branch of the Sweet Pea (Lathyrus odoratus). The 

 stem angular and scandent or supporting itself by the tendrils 

 or claspers of the leaves. The pinnate leaf furnished with 

 stipules or small leafy processes at its base. The place of 5 

 upper leaflets represented by so many undivided tendrils. The 

 peduncle or flower-stalk, supporting 2 flowers. 



Fig. 1. — The Legume or pod, the general fruit or pericarp of this 

 tribe of plants, dividing into 2 valves or portions, with but one 

 cavity or cell, and the seeds attached to the upper margin or 

 suture. 



Fig. 2. — The papilionaceous flower of Lathyrus sylvestris dis- 

 sected, a. The 5-toothed calyx. b. The vexillum, or ban- 

 ner, the larger upper petal, c. The ales, or wings, the 2 late- 

 ral petals, d. The carina or keel, formed of 2 petals coher- 

 ing by their 2 edges, but with 2 distinct claws, or narrow 

 bases, e. The 10 stamina, 9 united and 1 separate. /. The 

 pistillum. 



Fig. 3. — A raceme of the flowers of the Honey-locust ( Gledit- 

 schia triacanthos) , given as an example of a leguminous plant, 

 with a regular flower, consisting of a calyx and equal bordered 

 calycine corolla, a. The fertile flower, b. The staminife- 

 rous flower, c. The 1-seeded legume or loment of the G. 

 monosperma. 



Fig. 4. — The flower of a species of Petalostemon, in which 5 of 

 the filaments produce petals instead of anthers, as at a. b. The 

 stamens. 



PLATE IV. 



LABIATE FLOWERS. 



Fig. 1. — A branch of Ground- Ivy (Glechoma hederacea), with 

 opposite, petiolated, reniform leaves, crenated on the margin. 



