. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. BUDS AND STEMS 119. A tuber. Note the stems growing from the eyes at one end. IT- ^^^Y^l^^ ^ ^^^^?. Notice the marks or eyes on its surface. Find a little projection withm each eye. This is a bud. Immediately under It you will find a tmy scale which represents a leaf. Later we shall see that a bud on a stem always has the same relation to a leaf as does this bud to the tiny scale. In other words, the position is the same in each case, and the struc- ture may be said to be homologou
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. BUDS AND STEMS 119. A tuber. Note the stems growing from the eyes at one end. IT- ^^^Y^l^^ ^ ^^^^?. Notice the marks or eyes on its surface. Find a little projection withm each eye. This is a bud. Immediately under It you will find a tmy scale which represents a leaf. Later we shall see that a bud on a stem always has the same relation to a leaf as does this bud to the tiny scale. In other words, the position is the same in each case, and the struc- ture may be said to be homologous to that of the bud and leaf of an ordinary stem. Try to find out the arrangement of the leaves on the potato; they may be either opposite or alternately placed on the stem. See, also, if you can find the point at which the stem was attached to the parent plant. If a potato is cut in cross section it will be possible to find all the parts of a stem. The pith occupies the central portion; around this is the wood, which here looks hke a dark band. Out- side the wood we find the cortex, the potato being protected by the rather delicate epidermis. Cut a potato and a sweet potato in cross section; place each in red ink overnight. It will then be easy to compare the course taken by fluids in passing up a root and a stem. Cut out several eyes from healthy pota- toes. From one or two remove all of the flesh of the potato, and in the other speci- mens leave food supply intact. Does the stored food help the young plant in its growth ? Test for food stuffs in the potato. What foods are present? Reduced Stems. — In some plants the stem is so reduced as to be almost lost. This may be of a distinct advantage to the plant in enabling it to escape destruction from enemies. Such a plant is the common dandelion, which, because of its short stem, escapes grazing animals and the knives of lawn mow^ers. Many other low-lying weeds are partly immune from dangers which be- set taller plants. Bulbs.
Size: 1827px × 1367px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookpublishernewyorkamericanbookcompany, booksubjectbiology
