. Botany for agricultural students . Botany. PORELLA 415. into other kinds of work is spoken of as sterilization of sporog- enous tissue. One can now see that a sporophyte could become as complex as a Corn plant by becoming more and more multi- cellular while at the same time most of the cells were used in forming structures, such as roots, stems, and leaves. In this way sporophytes became more and more com- plex until the highest plant forms were pro- duced. Porella. — This Liverwort belongs to the Jungermaniales, which order contains the largest number of Liverworts. The Jungermaniales vary
. Botany for agricultural students . Botany. PORELLA 415. into other kinds of work is spoken of as sterilization of sporog- enous tissue. One can now see that a sporophyte could become as complex as a Corn plant by becoming more and more multi- cellular while at the same time most of the cells were used in forming structures, such as roots, stems, and leaves. In this way sporophytes became more and more com- plex until the highest plant forms were pro- duced. Porella. — This Liverwort belongs to the Jungermaniales, which order contains the largest number of Liverworts. The Jungermaniales vary widely in their moisture requirements, some being able to live in dry situations. They are especially abundant in the tropics where they grow on the trunks of trees, on leaves of other plants, and on the ground. Some have thallose game- tophytes like the Marchantiales, while others, known as foliose forms, have gametophytes that are differentiated into leaf- and stem- like structures and resemble the Mosses. Porella is one of the foliose forms of the Jungermaniales and is common on the trunks of trees and fallen logs in the north temperate regions. The character of the gametophyte is shown in Figure 370. It has a slender, creeping, branched, stem-like axis bearing two hor- izontal rows of larger leaves on the dorsal surface and one horizontal row of smaller leaves on the ventral surface. Although much more differentiated as to form, the gametophyte of Porella is much less differentiated as to tissues than the gametophyte of the Marchantias. The two kinds of sex organs may occur on the same plant or on different plants. The Archegonia occur in groups on the ends of short lateral branches. The antheridia occur in the axils of the leaves of certain branches which can be identified by the closely imbricated leaves. The sporophyte has a long stalk and the sporangium splits into four valves which spread out and allow the spores to escape. There is more sterilization of sporogenous
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
