52 PEOPAGATIOU- OF PLANTS. 



seen in the common lichens growiag on rocks and on the 

 old bark of trees. 



In the most familiar acceptance of the term as applied 

 to plants, a stem is that part bearing leayes and flowers. 

 The ordinary herbs or herbaceous plants do not produce 

 perennial woody stems, but annual flower stalks {caulis), 

 which may or may not bear true leaves in addition to 

 those organs generally accompanying the flowers. 



The stems of grasses are mostly hollow, jointed tubes, 

 living only a sufficient time to perfect their seed, 

 whether the period required is but a few weeks, as with 

 the common meadow grasses, or several years, as with 

 the great Bamboo of Oriental countries. It may be 

 mentioned, however, that while under purely natural 

 conditions the stems of such plants invariably perish 

 with the ripening of their seeds, it is not at all difficult 

 to prevent either, if the stems are required for other 

 purposes, which is often the case, as, for instance, the 

 stalks of the tropical Sugar Cane {Saccharum officinarum). 

 This plant has been so long and continuously propagated 

 by cuttings or " rattoons," that it no longer produces seed 

 under the artificial conditions to which it is subjected. 

 The Bamboos, Eeeds, and many other kinds of grasses, 

 may be readily propagated in the same way, and by pre- 

 venting the production of seeds they can be perpetuated 

 and multiplied almost without limit, even when no seeds 

 are produced. In the true Palms {Palmes), the stems 

 are perennial, and often attain to a very large size, liv- 

 ing to a great age and fruiting almost constantly. 



Among the Ferns (Filices), we find some with distinct 

 fruiting stalks, the seed-like organs being produced on 

 leafless, sporiferous stems, springing direct from the 

 crowns of the roots, while in others the sporangia are 

 found on the fronds only. Plants producing distinct 

 stems are termed caulescent, while those in which the 

 stem is inconspicuous are acaulescent — i, e., without a 



