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Revista de Biología Tropical, ISSN: 2215-2075 Vol. 69(3): 797-810, July-September 2021 (Published Aug. 09, 2021)
except in Nuytsia, where the central flower is
bisexual and the lateral flowers are pistillate or
staminate (Narayana, 1958a); lateral flowers
abort in some cases in this genus.
Gaiadendron punctatum has a septilocular
ovary, which is the greatest number of loc-
ules in the Loranthaceae. Nuytsia (Narayana,
1958a) and Lepeostegeres (Dixit, 1958) each
have three locules, while Atkinsonia, Amylothe-
ca (Raj, 1970), Lysiana (Narayana, 1958b) and
Peraxilla (Prakash, 1960) each have four. The
ovary is unilocular in the remaining genera of
the family (Kuijt, 2015).Nuytsia, Gaiadendron
and the genera of the tribe Elytrantheae all have
a mamelon, being amyliferous in G. punctatum
and in the tribe Elytrantheae (Johri et al., 1992)
and not being amyliferous in Nuytsia (Nara-
yana, 1958a). The mamelon in G. puntatum
is retained within the ovary without entering
the style, a condition also reported in Perax-
illa Tiegh. and Amylotheca Tiegh. (Prakash,
1960; Raj, 1970), while in Nuytsia, Lysiana
Tiegh. and Lepeostegeres Blume (Dixit, 1958;
Narayana, 1958a; Narayana, 1958b), the mam-
elon invades the hollow style. In Nuytsia the
mamelon remains separate from the adjacent
tissue, but in Lysiana and Lepeostegeres this
structure is fused with the ovary wall and the
tissues of the stigma.
The mamelon of Nuytsia does not have
amyliferous tissue, but the style does have
amyliferous parenchyma. Thus, the embryo
sacs can invade the style for quite a good
part of its length. The embryo sacs of Lysiana
and Lepeostegeres also enter the style due to
the invasion of the amyliferous tissue of the
mamelon into the lumen of the stylar canal
(Bhatnagar & Johri, 1983). The embryo sacs
of Gaiadendron, just like those of Peraxilla y
Macrosolen (Blume) Rchb., develop only up
to the base of the style because the mamelon
is short and there is no amyliferous tissue in
the style. The mamelon is fused with the ovary
wall in Gaiadendron, a condition also seen in
Lysiana and Lepeostegeres (Dixit, 1958; Nara-
yana, 1958b) but not in Nuytsia. The aforemen-
tioned characters suggest that Gaiadendron has
a greater affinity with the tribe Elytrantheae
than with Nuytsia.
Although Cocucci (1982) indicated that
Atkinsonia ligustrina has an amyliferous ovary
like that found in genera of the tribe Elytranthe-
ae, there is no direct evidence of this condition
in Atkinsonia according to the studies cited by
Cocucci (Garg, 1958; Prakash, 1961).
Calyculus, base of style and nectary: The
vascularization of the calyculus is different in
each of the three basal genera of Loranthaceae
(Table 2). The absence of bundles or tracheids
in the calyculus of Gaiadendron punctatum is
the state found in the rest of the Loranthaceae,
while only Nuytsia and Atkinsonia present
alternative states. This result supports the Su
et al., (2015) topology of (Nuytsia (Atkinsonia
(Gaiadendron (rest of the Loranthaceae)))).
It should be noted that the inconspicuous
calyculus of G. punctatum contrasts with that
of G. coronatum, in which the lobes are den-
tate, well differentiated, and persistent in fruit
(Kuijt, 2015).
Diverse types of nectaries have been
reported in Loranthaceae. In the Neotropical
clade Psittacanthinae, (sensu Nickrent et al.,
2010), the nectaries often form a disk or ring
between the base of the style and the base of
the petals. This ring usually has stomata and
subepidermal parenchyma with dark-staining
cellular contents, as can be seen in Peri-
stethium leptostachyum Kunth (Tiegh.) (Robles
et al., 2016), Psitacanthus Mart. (Robayo et
al., 2020), Passovia Karst., Aetanthus (Eichl.)
Engl. and Oryctanthus Eichl. (Suaza-Gaviria
et al., 2016). A different type of nectary found
at the base of the petals has been described in
Cladocolea Tiegh. (Cid-Villamil, 2006).
Nevertheless, it has been reported that
the basal genera Nuytsia (Narayana, 1958a),
Atkinsonia (Prakash, 1961) and few species of
the Tribe Elytrantheae have thickenings at the
base of the style (Amylotheca, Lepeostegeres:
respectively, Dixit, 1958; Raj, 1970). In some
of these cases, they have been interpreted
as possible nectaries (Lepeostegeres, Nuyt-
sia: respectively Narayana, 1958a; Raj, 1970)