-------------+-------------------------------------------------- | Macrospore (remains in = Large cell in center of | sporangium) nucellus which develops | embryo sac and endosperm | (remains in nucellus). Female | Female prothallium = Endosperm, in nucellus. gametophyte | (in sporangium) | Archegonia (female = Corpuscula, in endosperm. | sexual organs) | Egg = Maternal cell, or germ | cell. -------------+-------------------------------------------------- | Egg (fertilized) = Germ cell. | Young sporophyte = Pine embryo in nucellus | and integument. Young | Young sporophyte = Embryo | sporophyte | In remains of = Endosperm | | gametophyte = Nucellus | Seed. | And sporangium = Integument | | Surrounded by new | | growth of old | | sporophyte | -------------+---------------------------------------+---------- CHAPTER XXXV. MORPHOLOGY OF THE ANGIOSPERMS: TRILLIUM; DENTARIA. Trillium. =639. General appearance.=—As one of the plants to illustrate this group we may take the wake-robin, as it is sometimes called, or trillium. There are several species of this genus in the United States; the commonest one in the eastern part is the “white wake-robin” (Trillium grandiflorum). This occurs in or near the woods. A picture of the plant is shown in fig. 378. There is a thick, fleshy, underground stem, or rhizome as it is usually called. This rhizome is perennial, and is marked by ridges and scars. The roots are quite stout and possess coarse wrinkles. From the growing end of the rhizome each year the leafy, flowering stem arises. This is 20-30_cm_ (8-12 inches) in height. Near the upper end is a whorl of three ovate leaves, and from the center of this rosette rises the flower stalk, bearing the flower at its summit. =640. Parts of the flower. Calyx.=—Now if we examine the flower we see that there are several leaf-like structures. These are arranged also in threes just as are the leaves. First there is a whorl of three, pointed, lanceolate, green, leaf-like members, which make up the _calyx_ in the higher plants, and the parts of the calyx are _sepals_, that is, each leaf-like member is a _sepal_. But while the sepals are part of the flower, so called, we easily recognize them as belonging to the _leaf series_.