314 PHYLUM XIV. ANTHOPHYTA 
exocarp. Cherry, Peach or Almond flowers and fruits may be 
substituted for the Plum. 
(e) Dissect a flower of the Garden Pea (Pisum) so as to show 
the zygomorphy of the corolla, the ten curved stamens, the 
single, elongated and several-ovuled pistil. Study developed 
pods (legumes) and young seeds. Compare the zygomorphic, 
shallow-cupped Pea flower with the related actinomorphic 
Plum flower. The Sweet Pea (Lathyrus), Bean (Phaseolus), 
and Locust (Robinia) flowers are similar to those of the Pea. 
(f) Study the flowers and fruits of the Currant or Gooseberry 
(Ribes), observing their general resemblance to the Apple, but 
noting the bicarpellary pistil with parietal placentae and the 
reduced number of stamens. 
(g) Compare the flower of Oenothera with that of Spiraea 
noting the extreme elongation of the receptacular cup, which 
adheres to the united, many-seeded carpels; and the reduction 
of the stamens to two whorls. 
(h) Study macroscopically the mature sporophyte of a 
Prickly Pear (Opuntia), noting the small, narrow, fleshy, short- 
lived leaves on the young shoots. In longitudinal and cross- 
sections of the flowers make out the fleshy cup surrounding the 
compound ovary, and the many spirally arranged stamens, 
petals and sepals. Other genera of cactuses show a similar 
flower structure, and may be substituted for Opuntia, but the 
plants are mostly wholly leafless. 
(i) Examine macroscopically a staminate flower cluster (cat- 
kin) of the Walnut (Juglans) or Hickory (Hicoria) noting the 
crowded, small, many-stamened, apetalous flowers. Make 
cross and longitudinal sections of the pistillate flower showing 
the inferior ovary, surmounted by two large stigmas. Make 
comparative studies of the fruits and nuts. 
(j) Examine the staminate flower clusters of the Oak 
(Quercus) or Chestnut (Castanea), comparing the several 
staminate flowers with those of the preceding (7). As the 
leaves are unfolding, or soon after, find near the tips of the 
twigs the clusters of two or three pistillate flowers. Dissect 
these out from their involucres, and note the calyx borne on 
the edge of the thin receptacular cup which adheres to the tri- 
carpellary ovary. Examine ripe acorns which are found 
single seated in the cup-like involucre, or chestnuts which occur 
several together entirely enclosed in the prickly involucre. 
