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those of Triloboxylon Matten & Banks emend.
Scheckler & Banks (1971a) in having two pinnate
orders of branches and in being inserted distally.
Moreover, fertile organs in Triloboxylon show
two proximal dichotomies and sporangia are both
shorter and wider than those of the Moroccan
specimen (Table 1). Fertile organs in the latter
compare better to those of the genera Tetraxylop-
teris Beck emend. Hammond & Berry (2005)
(Table 1). However, branching in Tetraxylopteris
is not helical but typically opposite and decussate,
a pattern recognizable in both the vegetative and
fertile parts of this genus (Bonamo & Banks 1967;
Hammond & Berry 2005). A second difference in
the Moroccan specimen is that the proximal axis
of the fertile organ in Tetraxylopteris dichotomizes
twice rather than once, as in Triloboxylon.
Middle Devonian sediments of Imouzzer-
du-Kandar, a close locality from Central Morocco
(70 km NE of Dechra A¨t Abdallah), yielded par-
tially permineralized branch systems of aneurophy-
talean type (Fairon-Demaret & R ´ gnault 1986).
According to these authors, distinctive aneurophyta-
lean characteristics were the branching pattern, the
vascular architecture of the three-lobed stele and
the presence of thickened cortical cells. Due to the
lack of fertile remains, no generic designation was
assigned to this material. However, it is interesting
to note here that the resemblance of one specimen
with Rellimia was discussed (Fairon-Demaret &
R´gnault 1986, plate 3).
Fig. 3. Schematic reconstruction of a fertile organ of
Rellimia.
preserved: information on vegetative appendages is
lacking, and no anatomical data could be obtained.
The fertile organs of the Moroccan specimen
have typical aneurophytalean morphology in being
recurved adaxially. They demonstrate a complex
branching system comprising one level of dichot-
omy proximally and pinnate branching distally
(Fig. 3). On the basis of its spirally inserted, profu-
sely branched lateral fertile appendages, terminated
in narrow axes bearing dense masses of slender
elongate sporangia, this specimen is assigned to
the genus Rellimia Leclercq & Bonamo 1973. This
genus includes the single species R. thomsonii
(Dawson) Leclercq & Bonamo (1973), but the
Moroccan specimen is not well preserved enough
to be unequivocally assigned to that species. Poss-
ible differences are the number of pinnate orders
of branches and the size of individual sporangia
that seems larger in the specimen described here
(Table 1). The Moroccan specimen will therefore
be referred to as Rellimia sp.
Discussion
The earliest representative of the lignophytes?
The lignophyte clade includes the Euphylloph-
ytes (Fig. 4) that have the ability to produce
secondary phloem and xylem due to the presence
of a lateral meristem called vascular cambium. In
current phylogenies, the lignophytes encompass
the paraphyletic progymnosperms (Aneurophytales,
Archaeopteridales and Protopityales, not repres-
ented in Fig. 4) and the monophyletic spermato-
phytes (Crane 1985).
The earliest lignophytes belong to the Aneuro-
phytales and, possibly, to the Stenokoleales. The
plants included in the Stenokoleales Beck & Stein
are distributed within the two genera Stenokoleos
Hoskins & Cross and Crossia Beck & Stein.
Those plants are known exclusively from perminer-
alizations and range from Middle Devonian to
Lower Carboniferous (Beck & Stein 1993). The Ste-
nokoleales have mostly been described from US
localities; an occurrence of Crossia at Ronqui`res
(mid-Givetian, Belgium; Gerrienne et al. 2004) is
currently under investigation at Liege University.
Those plants are characterized by a three-ribbed
Comparison with other Aneurophytales
The morphology of aneurophytalean fertile organs
is highly distinctive, but shows a range of variation.
Fertile organs in the Moroccan specimen are much
larger and more complex than those of Aneurophy-
ton Kr¨usel & Weyland (Serlin & Banks 1975;
Schweitzer & Matten 1982). They also differ from
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