. Foundations of botany. THE STUDY OF PIGEON-WHEAT MOSS(POLYTKICHUM COMMUNE) 343. Occurrence. — This moss is widely distributed over the sur-face of the earth, and some of its relatives are among the bestknown mosses of the northern United States. Here it growscommonly in dry pastures or on hillsides, not usually in denselyshaded situations. 344. Form, Size, and General Characters. — Study several speci-mens which have been pulled up with root-hairs. Note the size,general form, color, and texture of all the parts of the plants exam-ined. Some of them probably bear spore-capsules or sporophytes
. Foundations of botany. THE STUDY OF PIGEON-WHEAT MOSS(POLYTKICHUM COMMUNE) 343. Occurrence. — This moss is widely distributed over the sur-face of the earth, and some of its relatives are among the bestknown mosses of the northern United States. Here it growscommonly in dry pastures or on hillsides, not usually in denselyshaded situations. 344. Form, Size, and General Characters. — Study several speci-mens which have been pulled up with root-hairs. Note the size,general form, color, and texture of all the parts of the plants exam-ined. Some of them probably bear spore-capsules or sporophytes likethose shown in Fig. 206, while others are without them. Sketch oneplant of each kind, about natm-al size. What difference is noticeable between the appearance of theleaves in those plants which have spore-capsules and those whichhave none ? Why is this ? 282 rOUNBATIONS OF BOTANY In some specimens the stem may be found, at a height of an inchor more above the roots, to bear a conical, basket-shaped Fig. 206. — A Moss, Catharinea. Tlie sporophytes of this moss are usually rather more slender than ashere represented. TYPES OF CRYPTOGAMS; BRYOPHYTES 283 out of the center of which a younger portion of the stem seems toproceed ; and this younger portion may in turn end in a similarenlargement, from which a still younger part proceeds. Note the difference in general appearance between the leaves ofthose plants which have just been removed from the moist collecting-box and those which have been lying for half an hour on the the leaves in both cases with the magnifying glass in order tofind out what has happened to them. Of what use to the plant isthis change ? Put some of the partially dried leaves in water, in a
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