Question

label figure 10.16 and 10.17

a. Look for tetrads of spores. Are the spores haploid or diploid The claters? 14) b. What is the function of the elaters? 2. Examine a prepared slide of a longitudinal section of Marcha prophytes. The sporophytes of Marchant are smaller and less conspicuous than those of the mosses. Several stages of development may be seen. Youn sporophytes show little cellular differentiation. In more mature sporophytes, a b al foot, a mid-region seta, and a swollen, terminal sporangium can be seen. 3. Within the sporangium are many spores and elongated, threadlike structures called claters. Examine these elaters, and note the spiral or braidlike nature of the cellulose walls. These elaters respond to changes in humidity by coiling and uncoiling within the sporangium. The spo- rangium may be partially enclosed by the remains of the archegonium, the calyptra, as in the mosses. 4. Label the calyptra, foot, seta, and sporangiom with spores in the mature sporophytes (Fig. 10.16). FIGURE 10.16 Marchantia sporophytes, 70X. EXERCISE 10 * Mosses, Liverworts and Hornworts 109

Answer 1

ULUM WILHA the sporangium. The po- rangium may be partially enclosed by the remains of the archegonium, the calyptra, as in the mosses. foot thallus sporangium + spores seta calyptra peridium

DIVISION Anthocerophyta (Hornworts) (A Photographic Atlas for the Botany Laboratory, 7e: p. 81) Anthoceros Examine a prepared slide of Anthoceros. These specimens are gametophyte plants with a sporophyte attached. The in the gametophyte thallus. Just above the foot is a re elongated appearance of the sporophyte is responsible for meristematic tissue. This basal meristem gives rise to the name of the group. Archegonia and antheridia are the cells found in the sporangium (capsule) above it. embedded within the gametophyte thallus. The sporophyte Label the gametophyte thallus, foot, basal meristem, and is an clongated, spikelike structure. The foot is also embedded sporangium with spores in the photograph of Anthoceros (Fig.10.17). sporangium with spores gametophyte thallus foot basal meristem FIGURE 10.17 Anthoceros thallus with sporophyte, 30 x.

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