that branch near the base of the phylogenetic trees
(¼“ancestral”), the life cycle has usually a single haploid
generation (the gametogen). (ii) Higher up in the trees, there
are digenetic diphasic life cycles, with alternation between a
haploid gametogen and a diploid sporogen (gametogenous
and sporogenous generations). (iii) Finally, in Streptobionta,
approaching the top of the tree, there is a steady reduction of
the importance of the gametogen, to only a few nuclei and
1
3
2
4
5
8
9
7
6
Undulipodial external scale
Undulipodial internal scale
Plasmalemma
Dynein arms
Unipartite
mastigoneme
B microtubule
A microtubule
Doublet
microtubule
Central
microtubules
Fig. 7.19 Theoretical cross section of an undulipodium of
Chlorobionta. Doublet microtubules are numbered 1–9. One of the
dynein arms of the first doublet is absent. The mastigonemes and
undulipodial scales are not present in most Chlorobionta (From Inouye
(1993), modified and redrawn)
Table 7.4 Some morphological and life cycle traits in Viridiplantae. The embryophytes, which are always multicellular, are not detailed here.
The taxa are arranged in the same order as in the phylogenetic tree of Fig. 7.17
Taxon
Uni- (1) or
multi-cellular
(X)
Sexual reproduction
present (P) or unknown
(?)
Fertilization
Life cycle
mono- (1) or
digenetic (2)
Ploidy n (haplophase), 2n
(diplophase) or n + n
(micthaplophase) and relative
importance of the phases
Streptobionta
Magnoliophyta (sensu lato) X
P
Siphonogamy 2
n <<< 2n
Filicophyta (sensu lato)
X
P
Oogamy
2
n << 2n
Bryophyta (sensu lato)
X
P
Oogamy
2
n > 2n
Coleochaetophyceae
X
P
Oogamy
1
n
Chaetosphaeridiophyceae
1
P
Oogamy
?
?
Zygnematophyceae
1 or X
P
Cystogamy
1
n
Charophyceae
X
P
Oogamy
1
n
Klebsormidiophyceae
X
P
Oogamy
?
?
Chlorokybophyceae
1
?
–
–
–
Mesostigmatophyceae
1
?
–
–
–
Chlorobionta
Cladophorophyceae
X
P
Planogamy
2
n = 2n
Bryopsidophyceae
X
P
Planogamy
2
n > n + n
Dasycladophyceae
X or 1
P
Planogamy
1
2n
Trentepohliophyceae
X
P?
Planogamy
?
?
Ulvophyceae
X
P
Planogamy
2
n = 2n
Trebouxiophyceae
1
P
?
?
?
Chlorophyceae
1
P
Planogamy,
Oogamy
1
n
Prasinophyceae
1
P
Planogamy
1
n
214
C.-F. Boudouresque
(¼“ancestral”), the life cycle has usually a single haploid
generation (the gametogen). (ii) Higher up in the trees, there
are digenetic diphasic life cycles, with alternation between a
haploid gametogen and a diploid sporogen (gametogenous
and sporogenous generations). (iii) Finally, in Streptobionta,
approaching the top of the tree, there is a steady reduction of
the importance of the gametogen, to only a few nuclei and
1
3
2
4
5
8
9
7
6
Undulipodial external scale
Undulipodial internal scale
Plasmalemma
Dynein arms
Unipartite
mastigoneme
B microtubule
A microtubule
Doublet
microtubule
Central
microtubules
Fig. 7.19 Theoretical cross section of an undulipodium of
Chlorobionta. Doublet microtubules are numbered 1–9. One of the
dynein arms of the first doublet is absent. The mastigonemes and
undulipodial scales are not present in most Chlorobionta (From Inouye
(1993), modified and redrawn)
Table 7.4 Some morphological and life cycle traits in Viridiplantae. The embryophytes, which are always multicellular, are not detailed here.
The taxa are arranged in the same order as in the phylogenetic tree of Fig. 7.17
Taxon
Uni- (1) or
multi-cellular
(X)
Sexual reproduction
present (P) or unknown
(?)
Fertilization
Life cycle
mono- (1) or
digenetic (2)
Ploidy n (haplophase), 2n
(diplophase) or n + n
(micthaplophase) and relative
importance of the phases
Streptobionta
Magnoliophyta (sensu lato) X
P
Siphonogamy 2
n <<< 2n
Filicophyta (sensu lato)
X
P
Oogamy
2
n << 2n
Bryophyta (sensu lato)
X
P
Oogamy
2
n > 2n
Coleochaetophyceae
X
P
Oogamy
1
n
Chaetosphaeridiophyceae
1
P
Oogamy
?
?
Zygnematophyceae
1 or X
P
Cystogamy
1
n
Charophyceae
X
P
Oogamy
1
n
Klebsormidiophyceae
X
P
Oogamy
?
?
Chlorokybophyceae
1
?
–
–
–
Mesostigmatophyceae
1
?
–
–
–
Chlorobionta
Cladophorophyceae
X
P
Planogamy
2
n = 2n
Bryopsidophyceae
X
P
Planogamy
2
n > n + n
Dasycladophyceae
X or 1
P
Planogamy
1
2n
Trentepohliophyceae
X
P?
Planogamy
?
?
Ulvophyceae
X
P
Planogamy
2
n = 2n
Trebouxiophyceae
1
P
?
?
?
Chlorophyceae
1
P
Planogamy,
Oogamy
1
n
Prasinophyceae
1
P
Planogamy
1
n
214
C.-F. Boudouresque