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from complete, it cannot be excluded that all of these groups, except the one containing
Sweetia
and
Leutzelburgia
, contain only nodulating genera.
Sweetia
and
Leutzelburgia
are grouped with
Vatairia
and
Vatairiopsis
, two non-nodulating genera formerly in
tribe Dalbergieae. Scattered among the groups of Sophoreae are some groups of non-
nodulating Swartzioids (Pennington et al., 2005).
1.3.2 Nodulating papilionoids with primitive nodule structure
Five genera, (
Andira, Cyclolobium, Dahlstedtia, Poecilanthe,
and
Hymenolobium
), all
with the 50kb inversion, are known to have bacteria retained within fixation threads
(Fig. 1.2D), rather than released into symbiosomes (Fig. 1.2; Chapter 5). This feature is
the norm in caesalpinioid legumes (see above) and has never been found in mimosoid
legumes. It is also not known from nodules in tribe Swartzieae, generally considered
to be basally branching within Papilionoideae. It is fair to say that the five genera listed
above have been rather a headache for taxonomists, using a wide array of characteris-
tics, but not including nodule structure.
Andira
and
Hymenolobium
, still formally placed
in tribe Dalbergieae, are now included in a separate clade, close to the non-nodulating
genera
Vatairia
and
Vatairiopsis
(Klitgaard & Lavin, 2005). The other three genera
were earlier placed in tribe Millettieae, but
Cyclolobium
and
Poecilanthe
have recently
been transferred to tribe Brongniartieae (Ross & Crisp, 2005), leaving
Dahlstedtia
in
Millettieae. The present constitution of tribe Brongniartieae is given in Table 1.7. The
large Australian component was formerly the
Templetonia
group of tribe Bossieaeeae
(see section 1.3.5). Even within their new home,
Cyclolobium
and
Poecilanthe
are placed
separate from the remainder of the tribe (Ross & Crisp, 2005). The only common
features for the five genera with primitive nodule structure are that all are woody
and all are found in South America, properties that are common to all but two of
the nodulating caesalpinioid legumes (see section 1.1). Little is known of the rhizobia
nodulating any of these genera or of other members of tribe Brongniartieae, with the
exception of the Australian genera
Hovea
and
Templetonia
. The former was found to be
nodulated only by bradyrhizobia in Southeast Australia (Lafay & Burdon, 1998) and
both are nodulated by the fast-growing strain NGR 234 (Pueppke & Broughton, 1999).
Tab l e 1 . 7
Nodulation in tribe Brongniartieae, genera as given in Ross & Crisp (2005)
Genus
Species
Nod.
Comment
Brongniartia
Kunth.
∼
63
1
98% spp. in Mexico, none in Australia
Cristonia
J.H. Ross
1
?
Ex
Templetonia
Cyclolobium
Benth
1
1
South America
Harpalyce
Mo¸ino & Sesse
24
2
Central America
Hovea
R. Br. ex W.T. Aiton
37
8
Australia
Lamprolobium
Benth.
2
1
Australia
Plagiocarpus
Benth.
1
?
North Australia
Poecilanthe
Benth
10-12
6
South America
Templetonia
R. Br. ex W.T. Aiton.
10
2
Australia
Thinicola
J.H. Ross
1
?
Ex
Templetonia
