"Leafy" liverworts (Fig. 20.8) are often abundant in tropical forests and in fog belts. They always have two rows of partially overlapping "leaves" whose cells contain distinctive oil bodies. The "leaves" have no midribs, and unlike the "leaves" of mosses, they often have folds and lobes. In the
388 Chapter 20
tropics, the lobes form little water pockets in which tiny animals are nearly always present. It has been suggested these water pockets may function like the pitchers of pitcher plants (discussed in Chapter 7). A third row of "under-leaves" is often present on the underside of "leafy" liverworts. The "underleaves" are smaller than the other "leaves" and not visible from the top. A few rhizoids that anchor the plants develop from the stemlike axis at the base of the "underleaves."
The archegonia and antheridia of the "leafy" liverworts are produced in cuplike structures composed of a few modified "leaves," either in the axils of "leaves" or on separate branches. At maturity, the sporophyte capsule may be pushed out from among the "leaves" as the seta elongates. When a spore germinates, it produces a protonema consisting of a short filament of photosynthetic cells. The protonema soon develops into a mature gametophyte plant.
Was this article helpful?
This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.