The leaves are perfectly smooth, dull purplish red on the lower side, and pale green with purplish blotches above. The epidermis may be very easily removed, and is perfectly colorless. Examined closely, longitudinal rows of whitish spots may be detected: these are the breathing pores. [Illustration: FIG. 81.--_A_, plant of the yellow adder-tongue (_Erythronium americanum_), × ⅓. _B_, the bulb of the same, × ½. _r_, roots. _C_, section of _B_. _st._ the base of the stem bearing the bulb for next year (_b_) at its base. _D_, a single petal and stamen, × ½. _f_, the filament. _an._ anther. _E_, the gynœcium (pistil), × 1. _o_, ovary. _st._ style. _z_, stigma. _F_, a full-grown fruit, × ½. _G_, section of a full-grown macrosporangium (ovule), × 25: i, ii, the two integuments. _sp._ macrospore (embryo sac). _H_, cross-section of the ripe anther, × 12. _I_, a single pollen spore, × 150, showing the two nuclei (_n_, _nʹ_). _J_, a ripe seed, × 2. _K_, the same, in longitudinal section. _em._ the embryo. _L_, cross-section of the stem, × 12. _fb._ fibro-vascular bundle. _M_, diagram of the flower.] A cross-section of the stem shows numerous whitish areas scattered through it. These are the fibro-vascular bundles which in the monocotyledons are of a simple type. The bulb is composed of thick scales, which are modified leaves, and on cutting it lengthwise, we shall probably find the young bulb of next year (Fig. _C_, _b_) already forming inside it, the young bulb arising as a bud at the base of the stem of the present year. The flower is made up of five circles of very much modified leaves, three leaves in each set. The two outer circles are much alike, but the three outermost leaves are slightly narrower and strongly tinged with red on the back, completely concealing the three inner ones before the flower expands. The latter are pure yellow, except for a ridge along the back, and a few red specks near the base inside. These six leaves constitute the perigone of the flower; the three outer are called sepals, the inner ones petals. The next two circles are composed of the sporophylls bearing the pollen spores.[12] These are the stamens, and taken collectively are known as the "_Andrœcium_." Each leaf or stamen consists of two distinct portions, a delicate stalk or "filament" (_D_, _f_), and the upper spore-bearing part, the "anther" (_an._). The anther in the freshly opened flower has a smooth, red surface; but shortly after, the flower opens, splits along each side, and discharges the pollen spores. A section across the anther shows it to be composed of four sporangia or pollen sacs attached to a common central axis ("connective") (Fig. _H_). [12] The three outer stamens are shorter than the inner set.