pine - 79 - = / 79 = . Name_ Pinus Life Cycle You have...

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79 - = / 79 = . Name_______________________________ Pinus Life Cycle You have observed some gymnosperm diversity last week; today you will observe the details of the life cycle of Pinus , one of the most common conifers (Coniferophyta). This life history is similar to that of all of the gymnosperms, although the details might vary. For example, while the life cycle of some pines is a two-year process, in other conifers and most other gymnosperms it is a one-season process. All the gymnosperms are heterosporous with the megasporophylls and the microsporophylls grouped together in separate cones, but most gymnosperms are dioecious with only one type of cone (male or female but never both) on a particular individual. Pine, however, is monoecious; the microsporangiate cones occur near the ends of branches and the megasporangiate cones are found at the apex. Other conifers include: spruce, fir, hemlock, redwood, etc., as well as the southern hemisphere podocarps and araucarias. It includes the largest and the oldest living individual organisms known. •Observe branches of a few representative genera available in the laboratory. On your walks around campus, you will see others and might make some observations as you go along. Note that some genera, such as Juniperis , have two types of foliage leaves: longer needle-like leaves and much smaller scale leaves. Since the needle leaves are characteristic of young plants, they are referred to as JUVENILE leaves. Heterophylly such as this occurs in a number of angiosperms as well. The prefix Hetero- means _________________; the suffix -phylly means _____________. Observe a Pinus resinosa leaf cross section. This species of pine has lots of resin (no, duh!). The mesophyll resin ducts in the mesophyll. The epidermis cutin. (hint: look at the higher magnifications!) The guard cells the epidermis. How would you describe the shape of mesophyll cells?_______________________________ Inside the mesophyll there is an endodermis surrounding the vascular tissue that has awesome Casparian strips; if you have not seen a strip well, this is your best chance this semester! What color are the Casparian strips?______________________________________________ Between the endodermis and the vascular bundles there is a layer called transfusion tissue. Is transfusion tissue is . Observe the xylem and phloem. The arrangement is . Considering the position of xylem and phloem, the flat epidermis is the one. Observe a cross section of a young pine stem. This stem is surrounded by pairs of leaves (also caught in the cross-section). There are three views here at various magnifications. The leaves face each other with epidermi in contact. The leaf pair closest to the stem (at 1 o'clock) shows more leaves than just two.
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pine - 79 - = / 79 = . Name_ Pinus Life Cycle You have...

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