Agriculture Reference
In-Depth Information
(in Lewis et al., 2005, Mimozygantheae is retained). All tribes are due for changes,
the most comprehensive of which are in Acacieae, which contains the single genus
Acacia
.
Nodules in all mimosoid legumes studied are indeterminate, but vary considerably in
morphology and whether or not they are branched. Structurally, none is known to have
bacteroids retained within infection threads as they are in most Caesalpinioideae and
some Papilionoideae. This is interesting in view of the possible position of Mimosoideae
with respect to Caesalpinioideae in Fig. 1.3 and will be explored further in Chapter 3.
1.2.1 Acacieae
In Lewis (2005b), tribe Acacieae has one genus,
Acacia
. It has been known for decades
that
Acacia
is not monophyletic, and for many years it has been divided into three
sub-genera,
Acacia
,
Aculeiferum
and
Phyllodineae
(also called
Heterophyllum
). Generic
names have been suggested for these, but not widely accepted. This may be just as
well as it now appears that there should be at least five genera arising out of
Acacia
.
These are listed in Table 1.3. In Lewis (2005b), the
A. coulteri
group is referred to as
'genus X'. This has now been named
Mariosousa
(Seigler et al., 2006). As well as the
number of genera being in doubt (more may yet be added) the tribal affinities remain
unclear. The suggestions in Table 1.3 may be altered when more taxa are sampled, but
it is interesting that species of the seed-predating bruchid beetles support this tribal
arrangement (Kergoat et al., 2007). If further evidence supports the divisions given
in Table 1.3, then tribe Acacieae will cease to exist. Added to the scientific confusion
are considerations of national pride. Many Australians regard acacias as part of their
natural heritage, even though they usually refer to them as wattles, and wish to use the
generic name
Acacia
for sub-genus
Phyllodineae
. Others, including some Australians,
believe that the usual procedures should be followed, in which case sub-genus
Acacia
should retain that name. For this reason the old terms have been retained in Table
1.3. However, the subdivisions there have significance for symbiotic properties, which
is why the controversy over terminology has been engaged, rather than opting for a
quiet life!
Tab l e 1 . 3
Possible sub-division of
Acacia
into five genera and re-assignment into tribes. Based on
Maslin et al. (2003), Seigler et al. (2006) and Rico-Arce (2007)
Sub-genus
Species
Geographical range
Tribe?
Acacia
161
Mainly Africa and South America, some
in Asia and Australia
Mimoseae
Aculeiferum
203
Section Aculeiferum. Africa, Asia,
Ingeae
Section Monacanthea, pan-tropical
Acaciella
14
reinstatement of an old genus for
Aculeiferum
, section Filicinae New World
Mariosousa
13
A. coulteri
group, New World
Phyllodineae
∼
960
Mainly Australia, some Asia
Ingeae
