Figure 29.16 The life cycle of Polytrichum, a moss (Layer 1)

Figure 29.16 The life cycle of Polytrichum, a moss (Layer 2)

Figure 29.16 The life cycle of Polytrichum, a moss (Layer 3)

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The Life Cycle of a Polytrichum Moss (see prev slide)1) Spores develop into protonemata.2)The haploid protonemata produce “buds” that grow into gameto-phytes.3) Most mosses have separate male and female gametophytes, with

antheridia and archegonia respectively.4) A sperms swims through a film of moisture to an archegonium

and fertilizes the egg.5) The diploid zygote develops into a sporophyte 6) The sporophyte grows a long stalk, or seta, that emerges from the

archegonium. 7) Attached by its foot, the sporophyte remains nutritionally

dependenton the gametophyte.8) Meiosis occurs and haploid spores develop in the sporangium of

the sporophyte. When sporangium lid pops off, the peristome “teeth” gradual release of the spores.

Figure 29.16x Moss life cycle

Figure 29.x1 Polytrichum moss leaf section

Figure 29.17 Sporophyte of Marchantia, a liverwort

Figure 29.18 A moss sporangium with a “spore-shaker” tip