<Ul> <Li> Both of similar motility . Species of Ulva, the sea lettuce, have gametes which all have two flagella and so are motile . However they are of two sizes: larger' female' gametes and smaller' male' gametes . </Li> <Li> One large and sessile, one small and motile (oogamy). The larger sessile megagametes are eggs (ova), and smaller motile microgametes are sperm (spermatozoa, spermatozoids). The degree of motility of the sperm may be very limited (as in the case of flowering plants) but all are able to move towards the sessile eggs . When (as is almost always the case) the sperm and eggs are produced in different kinds of gametangia, the sperm - producing ones are called antheridia (singular antheridium) and the egg - producing ones archegonia (singular archegonium). Gametophyte of Pellia epiphylla with sporophytes growing from the remains of archegonia . <Ul> <Li> Antheridia and archegonia occur on the same gametophyte, which is then called monoicous . (Many sources, including those concerned with bryophytes, use the term' monoecious' for this situation and' dioecious' for the opposite . Here' monoecious' and' dioecious' are used only for sporophytes .) The liverwort Pellia epiphylla has the gametophyte as the dominant generation . It is monoicous: the small reddish sperm - producing antheridia are scattered along the midrib while the egg - producing archegonia grow nearer the tips of divisions of the plant . </Li> <Li> Antheridia and archegonia occur on different gametophytes, which are then called dioicous . The moss Mnium hornum has the gametophyte as the dominant generation . It is dioicous: male plants produce only antheridia in terminal rosettes, female plants produce only archegonia in the form of stalked capsules . Seed plant gametophytes are also dioicous . However, the parent sporophyte may be monoecious, producing both male and female gametophytes or dioecious, producing gametophytes of one gender only . Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells . </Li> </Ul> </Li> </Ul> <Li> Both of similar motility . Species of Ulva, the sea lettuce, have gametes which all have two flagella and so are motile . However they are of two sizes: larger' female' gametes and smaller' male' gametes . </Li> <Li> One large and sessile, one small and motile (oogamy). The larger sessile megagametes are eggs (ova), and smaller motile microgametes are sperm (spermatozoa, spermatozoids). The degree of motility of the sperm may be very limited (as in the case of flowering plants) but all are able to move towards the sessile eggs . When (as is almost always the case) the sperm and eggs are produced in different kinds of gametangia, the sperm - producing ones are called antheridia (singular antheridium) and the egg - producing ones archegonia (singular archegonium). Gametophyte of Pellia epiphylla with sporophytes growing from the remains of archegonia . <Ul> <Li> Antheridia and archegonia occur on the same gametophyte, which is then called monoicous . (Many sources, including those concerned with bryophytes, use the term' monoecious' for this situation and' dioecious' for the opposite . Here' monoecious' and' dioecious' are used only for sporophytes .) The liverwort Pellia epiphylla has the gametophyte as the dominant generation . It is monoicous: the small reddish sperm - producing antheridia are scattered along the midrib while the egg - producing archegonia grow nearer the tips of divisions of the plant . </Li> <Li> Antheridia and archegonia occur on different gametophytes, which are then called dioicous . The moss Mnium hornum has the gametophyte as the dominant generation . It is dioicous: male plants produce only antheridia in terminal rosettes, female plants produce only archegonia in the form of stalked capsules . Seed plant gametophytes are also dioicous . However, the parent sporophyte may be monoecious, producing both male and female gametophytes or dioecious, producing gametophytes of one gender only . Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells . </Li> </Ul> </Li> <Ul> <Li> Antheridia and archegonia occur on the same gametophyte, which is then called monoicous . (Many sources, including those concerned with bryophytes, use the term' monoecious' for this situation and' dioecious' for the opposite . Here' monoecious' and' dioecious' are used only for sporophytes .) The liverwort Pellia epiphylla has the gametophyte as the dominant generation . It is monoicous: the small reddish sperm - producing antheridia are scattered along the midrib while the egg - producing archegonia grow nearer the tips of divisions of the plant . </Li> <Li> Antheridia and archegonia occur on different gametophytes, which are then called dioicous . The moss Mnium hornum has the gametophyte as the dominant generation . It is dioicous: male plants produce only antheridia in terminal rosettes, female plants produce only archegonia in the form of stalked capsules . Seed plant gametophytes are also dioicous . However, the parent sporophyte may be monoecious, producing both male and female gametophytes or dioecious, producing gametophytes of one gender only . Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells . </Li> </Ul>

How do the spores and the cells of the leaf vary in their chromosome number