EXPLANATION OF THE PLATES. 
55 
veloped fruit; 3, fragment of the bark of the lower part of the plant, with several large hunches 
of spines. 
Pig. 4 _ 5 . Opuntia procumbens, E. & B.: 4, part of a joint; 5, larger bunch of spines from 
another specimen. 
Pl. YII, Fig. 1-2. Opuntia occidentalis, E. & B.: 1, joint of the usual shape and size; 
2, fruit. 
Fig. 3-4. Opuntia angustata, E. & B.: 3, a large and less spinous joint with a sterile 
degenerate spinous fruit; 4, a smaller, more spinous joint with a full grown ripe fruit. 
Pl. YIII, Fig. 1. Opuntia Engelmanni, var. cyclodes, E. & B.: with ripe fruit. 
Fig. 2-3. Opuntia tortispina, E. & B. : 2, fragment of a joint with fewer spines and ripe 
fruit; 3, part of a more spiny joint. 
Pl. IX, Fig. 1-5. Opuntia camanchica, E. & B. : 1, a joint with shorter and lighter colored 
spines; 2, a joint with larger and darker spines ; 3, fragment of a joint with more numerous 
an, docwded spines ; 4 and 5, ripe fruit of the smaller and largest size. 
Fig. 6-8, Opuntia mojavensis, E. & B.: 6, a younger bunch of spines • 7, another from the 
oldest part of the plant; 8, a sterile and degenerate fruit. 
Pl. X. Fig. 1-2. Opuntia vulgaris, Mill.: 1, a young joint with leaves, the older one has 
a single spine and hears, a flower hud ; 2, a single leaf magnified 4 diameters. The figures 
of this species have been introduced to exhibit the diagnostic characters and its difference from 
the next species. 
Fig. 3-5. Opuntia Bafinesquii, E.; 3, an older joint with a flower and a hud, and a younger 
half-grown joint with leaves. This represents the spinous form common in Illinois, Missouri, 
and Arkansas. 4, an older joint of the variety with few spines, hearing numerous fruits of 
different shapes, as they often occur in the same plant; 5, two leaves of different sizes mag¬ 
nified 4 diameters. 
Pl. XI, Fig. 1, Opuntia Rafinesquii, var. minor, E.: the larger joint spineless, the upper 
one spiny on the margin. 
Fig. 2-3. Opintia Rafinesquii, var. grandiflora, E.: 2 ; a joint with flower ; 3, fruit. 
Fig. 4. Opuntia fuscoatra, E.: a joint with a young fruit just after flowering, fragment of 
an older, very bristly, joint visible. 
Pl. XII. Fig. 1-3. Opuntia cymochilas, E. & B.: 1, a joint; 2, a single hunch of spines ; 
3, ripe fruit. 
Fig. 4-6. Opuntia stenochila, E. & B.: 4, a joint ; 5 and 6, a smaller and large fruit. 
Fig. 7-8. Opuntia fusiformis, E. & B.: 7, a joint; 8, a fruit. 
Fig. 9. Opuntia bracayarthra, E. & B.: a whole plant with two withered flowers. 
Pl. XIII. Fig. 1-5. Opuntia basllaris, E. & B.: 1, a joint somewhat shrivelled as it appears 
in winter ; a late young joint near its base appears more plump and fresh ; 2, flower ; 3, style ; 
4, undeveloped sterile fruit; 5, a whole plant reduced in size to show the singular manner of 
growth. 
Fig. 6-7. Opuntia sph^erocarpa, E. & B.: joint and fruit. 
Fig. 8-11. Opuntia erinacea, E. & B.: 8, joint of the usual shape, (only partly finished;) 
9 and 10, hunches of spines ; 11, fruit. 
Pl. XIY. Fig. 1-3. Opuntia Missouriensis, var. rufispinis, E. & B.: 1, a joint, (only partly 
completed ;) 2, a very full hunch of spines ; 3, fruit. 
Fig. 4. Opuntia Missouriensis, var. platycarpa, E.: fruit. 
Fig. 5-7. Opuntia Missouriensis, var. microsperma, E.: 5, joint (unfinished) with flower ; 6, 
bunch of spines ; 7, fruit. 
Fig. 8-10. Opuntia Missouriensis, var. albispina, E. & B. : 8, joint (unfinished); 9, bunch 
of spines ; 10, fruit. 
Pl. XV, Fig. 1-4. Opuntia Missouriensis, var. trichophora, E. & B. : 1, part of an old stem 
