. A popular description of the common Oregon ferns; contribution from the Herbarium of the University of Oregon. nnulusstraightens with more or less of a snap, scattering the spores tosome distance. If the spores meet with favorable conditions they II illustrates a number of stages of this growth. At first thespore sends out a little root (r) and a short chain of cells (p).These continue to differentiate, becoming flat and leaf-like, Fig. leaf-like form is known as a prothallus and often is a quarterof an inch or more across. The spore disappears, the prothallusbecomes a
. A popular description of the common Oregon ferns; contribution from the Herbarium of the University of Oregon. nnulusstraightens with more or less of a snap, scattering the spores tosome distance. If the spores meet with favorable conditions they II illustrates a number of stages of this growth. At first thespore sends out a little root (r) and a short chain of cells (p).These continue to differentiate, becoming flat and leaf-like, Fig. leaf-like form is known as a prothallus and often is a quarterof an inch or more across. The spore disappears, the prothallusbecomes attached by little root-like outgrowths and on its underside develops bottle-shaped egg cases containing a single egg each,and spherical sperm cases containing numerous sperms which havethe power of locomotion by means of vibrating threads attached toone end. When the eggs and sperms are ripe a single sperm passesdown to the egg in its case. The egg and the sperm each containsa still more microscopic portion called the nucleus in which, it isbelieved, reside hereditary characteristics. The union of the sperm. ?M <£. THE COMMON OREGON FERNS with the egg brings about a mingling of these characteristics, andis called fertilization. From this fertilized egg the new fern grows. ANALYTICAL KEY. It is customary to divide the plant kingdom into four groups:1. The Spermatophytes or Seed Plants; 2. The Pteridophytes orFern Plants; 3. The Bryophytes or Moss Plants; 4. The Thallo-phytes or the remaining lower forms. Sometimes the first group is spoken of as Phenogam, meaningevident marriage, because the method of reproduction is clearlyseen. The last three would be called Cryptogams or hidden mar-riage, because by the earlier botanist the reproduction was not wellunderstood, although it is now perfectly clear. Pteridophyte is a compound of two Greek words meaning fernand plant. This group includes a number of plants beside the trueferns such as the Horsetail Rushes, the Club Mosses and
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