Journal
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Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
Raju et al.
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Floral biology
The flowers open during 16:00–18:00 hr with
maximum flower production at 17:00hr (Image 1
e–k). Anther dehiscence occurs following anthesis
by longitudinal slits. Each anther produces 4136±192
pollen grains and the total pollen output per flower is
5,25,272±12,408. The pollen-ovule ratio varies from
13,833 to 25,013. The pollen grains are creamy-white,
triangular, tricolporate, triangular, 16.6µm in size,
powdery and fertile (Image 1o). The apertures appear
as short furrows in a thickened portion of the wall.
The distinctive pattern seen in polar view is formed by
thinning of the exine. Most of the pollen is dislodged as
single grains and it enters the ambient environment by
wind. Two peak pollen concentrations were recorded,
one with 17,832 pollen grains per m
3
of air sampled
in the evening hours between 17:00 and 20:00 hr and
another with 5,721 pollen grains per m
3
of air sampled
in the morning hours between 07:00 and 10:00 hr. In the
circadian cycle, the pollen grain concentrations varied
between 17,832 and 843 for cubic meter of air sampled.
The pollen concentration at peak pollen release hour
(19:00hr) at a distance of 0m was 17,832, at 5m 15,821,
at 10m 12,981, at 15m 7,432, at 20m 1500, and at 25m
Image 1. Syzygium alternifolium: a - Habitat; b - Leaf flushing; c -Flowering phase; d -A cluster of inflorescences with buds and flowers;
e - Mature buds; f-k - Different stages of anthesis; l. & m - Calyx cup with centrally located ovary terminated with simple stigma; n - Ovules;
o - Pollen grains. © Prof. A.J. Solomon Raju.
a
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Journal
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Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
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659. The pollen concentration at second peak hour
(09:00hr) was 5,721 at 0m, 4057 at 5m, 3947 at 10m,
3254 at 15m, 2874 at 20m and 1647 at 25m. The stigma
receptivity begins at 20:00hr and remains until the end
of 2
nd
day. The stamens fall at the 2
nd
day of flower life
while the remaining parts of the flower remain intact
for five days if not pollinated. In pollinated flowers,
the calyx cup is persistent and the fruit emerges out
when fully grown. The nectar is secreted in the orange
coloured part of the cup continuously for a period of
four days from the time of anthesis. A total of 12.7±4.32
µl of nectar is produced in the total life span of the
flower. The nectar sugar concentration is 16.44±3.1 %;
the sugars include sucrose (2.55µg), fructose (2.37µg)
and glucose (0.13µg). The nectar includes six essential
and nine non-essential amino acids. The essential
amino acids are arginine, histidine, lysine, threonine,
tryptophan and valine. The non-essential amino acids
are alanine, aspartic acid, cysteine, cystine, glutamic
acid, glysine, hydroxyproline, serine and tyrosine. The
total protein content in the nectar is 2.55µg.
Flower visitors and pollination
The flowers completely expose the anthers as well
as the stigma. The flower visitors accessed the floral
rewards with great ease. A total of 33 species consisting
of bees, wasps, flies, beetles, butterflies (diurnal
foragers), the hawk moth (crepuscular forager), and
the reptilian (nocturnal forager) was recorded (Table
2). The bees included Apis dorsata (Image 2c), A. cerana
(Image 2d), A. florea, Trigona iridipennis (Image 2e),
Amegilla sp. (Image 2f) and Stizus sp. (Image 2g). Of
these, Trigona bees foraged for nectar and also pollen,
while all others for nectar only. The wasps were nectar
Tree No.
Flowering season 2012
Flowering season 2013
First flowers
Last flowers
Total flowering days
First flowers
Last flowers
Total flowering days
1.
--
--
--
--
--
--
2.
--
--
--
--
--
--
3.
19 April
7 May
20
19 April
10 May
22
4.
--
--
--
--
--
--
5.
--
--
--
--
--
--
6.
18 April
6 May
19
--
--
--
7.
--
--
--
18 April
8 May
21
8.
26 April
14 May
19
--
--
--
9.
--
--
--
--
--
--
10.
--
--
--
--
--
--
11.
--
--
--
14 April
6 May
22
12.
--
--
--
--
--
--
13.
--
--
--
--
--
--
14.
26 April
14 May
19
19 April
14 May
26
15.
--
--
--
13 April
7 May
25
16.
--
--
--
--
--
--
17.
26 April
11 May
16
--
--
--
18.
--
--
--
14 April
7 May
23
19.
19 April
11 May
23
--
--
--
20.
21 April
6 May
16
--
--
--
21.
--
--
--
--
--
--
22.
--
--
--
--
--
--
23.
19 April
11 May
23
20 April
10 May
21
24.
17 April
7 May
21
18 April
6 May
19
25.
--
--
--
17 April
5 May
19
Table 1. Flowering phenology of Syzygium alternifolium
17 April - 14 May 13 April - 14 May. Flowering days: 16–23 (Mean 19 days) 19–26 (22 days)
Journal
of
Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
Raju et al.
6159
foragers and they were Eumenes sp. (Image 2h), Vespa
cincta (Image 2i) and V. orientalis (Image 2j). Both
the bees and wasps were regular foragers. Flies were
occasional nectar foragers and they were Chrysomya
megacephala (Image 2k) and Helophilus sp. (Image 2l).
Beetles were Popillia impressipyga (Image 2m) and
one unidentified species (Image 2n); the former was a
resident forager feeding on flower parts and contributed
to 26% of flower damage in 2011, 20% in 2012 and 6%
depending on flowering intensity while the latter was an
occasional nectar forager. The butterflies were regular
foragers and they were Papilio polytes (Image 3a),
Graphium nomius, Catopsilia pyranthe (Image 3b) , C.
pomona (Image c,d) , Euploea core (Image 3e) , Tirumala
limniace (Image 3f) , Precis iphita (Image 3g) , Junonia
lemonias (Image 3h) , Melanitis leda (Image 3i) , Danaus
genutia (Image 3j) , Neptis hylas (Image 3k) , Mycalesis
perseus (Image 3l) , Moduza procris, Arhopala amantes
(Image 3m), Pseudocoladenia indrani (Image 4a), Borbo
cinnara (Image 4b) , Hasora chromus (Image 4c) and
Celaenorrhinus ambareesa (Image 4d). The sphingid,
Cephonodes hylas (Image 4e) was the only diurnal moth
visiting the flowers regularly. The African fat-tailed
gecko, Hemitheconyx caudicinctus was a resident nectar
Image 2. Syzygium alternifolium: a - Bud infestation; b – Larva; c - Apis dorsata; d - Apis cerana; e - Trigona iridipennis; f - Amegilla sp.;
g - Stizus sp.; h - Eumenes sp.; i - Vespa cincta; j - Vespa orientalis; k - Chrysomya megacephala; l - Helophilus sp.; m - Popillia impressipyga;
n - Beetle (unidentified); o - Hemitheconyx caudicinctus. © Prof. A.J. Solomon Raju.
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Journal
of
Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
Raju et al.
6160
forager during night time from 0600–1000 hr (Image
2o).
The first visitor to just open flowers in the evening
was the diurnal hawk moth, Cephonodes hylas; it
continued its foraging from 16:00–19:00 hr. The same
moth was the first visitor to the flowers in the morning
and it foraged from 06:00–09:00 hr (Fig. 7). All other
insects visited the flowers from 07:00–12:00/13:00 hr
(Fig. 1–6); the flies made a few visits during 15:00–16:00
hr (Fig. 3). The intense foraging activity was recorded
during 09:00–11:00 for most of the insects. Of the total
foraging visits made by insects except beetles during the
3-year period, bees constituted 25%, wasps 15%, flies
3%, butterflies 50% and hawk moth 7% (Fig. 8). The
honey bee, A. dorsata, wasps, butterflies and the hawk
moth foraged for nectar very frequently between closely
and distantly spaced conspecific trees while other bees,
the unidentified beetle and the gecko tended to stay
mostly on the same tree for forage collection.
Figure 1. Hourly foraging activity of bees on Syzygium alternifolium
Figure 2. Hourly foraging activity of wasps on Syzygium alternifolium
Time (hr)
Time (hr)
Journal
of
Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
Raju et al.
6161
Flower bud as oviposition site for an unidentified moth
A moth species (unidentified) used the flower buds
as oviposition site. It deposited its eggs in young flower
buds and the emerged larvae consumed the entire bud
over a period of approximately 3–4 days (Image 2a,b).
The percentage of infested flower buds is 21% in 2011,
17% in 2012 and 4% in 2013. Consolidated mounds
formed by buds and flowers were also found and such
flowers subsequently fell off (Image 4f). These infested
flowers were found on all flowering branches in 2011,
randomly in 2012 and rarely in 2013. These bud and
flower infestations were found be to be related to the
intensity of flowering in each study year.
Image 3. Syzygium alternifolium: a - Papilio polytes; b - Catopsilia pyranthe; c. & d - Catopsilia pomona; e - Euploea core; f -Tirumala
limniace; g - Precis iphita; h - Junonia lemonias; i - Melanitis leda; j - Danaus genutia; k - Neptis hylas; l - Mycalesis perseus; m - Arhopala
amantes. © Prof. A.J. Solomon Raju.
Pollination mode
No. of flowers
bagged/tagged/
pollinated
No. of fruits
produced
Fruit set
(%)
Autogamy (bagged)
366
0
0
Autogamy (manual
pollination, bagged)
75
0
0
Geitonogamy (manual
pollination, bagged)
80
0
0
Xenogamy (manual
pollination, bagged)
60
34
57
Open-pollination
(Flowers tagged prior
to anthesis)
1030
116
11
Table 2. Results of breeding systems in Syzygium alternifolium
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Journal
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Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
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Breeding and fruiting behavior
Hand-pollination experiments indicated that
autogamy and geitonogamy are non-functional while
xenogamy is the only mode of pollination for fruit set.
In this mode, fruit set stands at 56% while in open-
pollination mode, it is 11% only (Table 3). The fertilized
flowers grow, mature and ripen within two months
(Image 4g-k). Fruit exhibits different colours - green,
light purple, dark purple and violet during growing and
maturing phase (Image 4l). It is a globose berry, luscious,
fleshy, 25–30 mm in diameter and edible. It has a
combination of sweet, mildly sour and astringent flavor
and colours the tongue purple when eaten. The green
and light purple fruits are very tasty and sweet while the
dark purple and violet ones are sweet and bitter. Each
fruit produces a single large seed only. The fruits fall off
during late July–August. The locals were found to collect
ripe fruits from trees and fallen fruits from the ground
since they are edible and have commercial value.
Seedling ecology
The habitat of the plant is rocky with steep slope
covered with little litter and moisture. The seedlings
recorded in the area were 58 in 2011, 32 in 2012 and
17 in 2013. These were subjected to drought stress
due to erratic rainfall. Further, extensive and robust
grass cover during that period was found to be having
impact on the surviving seedlings of the plant. Finally,
Image 4. Syzygium alternifolium: a - Pseudocoladenia indrani; b - Borbo cinnara; c - Hasora chromus; d - Celaenorrhinus ambareesa; e -
Cephonodes hylas; f - Infestation of buds and flowers; g - Fruiting phase; h-k - Stages of fruit maturation; l - Ripen fruits; m-p - Stages of seed
germination and seedling formation. © Prof. A.J. Solomon Raju.
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Journal
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Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
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27 seedlings in 2011, 16 in 2012 and seven in 2013 have
established and are growing continually at slow pace.
The soil analysis for available nitrogen (N), phosphorous
(P) and potassium (K) indicated that N is 270 kg/ha, P
13.57 kg/ha and K 282 kg/ha. These values show that
these nutrients are not present in optimal levels and
hence there is a deficiency in essential nutrients in the
soil. The seeds sown in experimental bags showed that
seeds germinate within two weeks and form seedlings
subsequently (Image 4m-p). The seed germination rate
is 74%.
DISCUSSION
S. alternifolium is a semi-evergreen mass-flowering
tree species in the study area. It is not only endemic but
also endangered due to its declining population. The
plant is not found in some sites where it was reported
by previous workers as cited above. It is exploited
for various local uses and hence it has now attained
“Endangered” status. It qualifies for inclusion in the
IUCN Red List.
In Syzygium genus, the flowering pattern is of two
types, mass flowering and short-period steady state
flowering but most species exhibit mass flowering such
Figure 3. Hourly foraging activity of flies on Syzygium alternifolium
Figure 4. Hourly foraging activity of Papilionid and Pierid butterflies on Syzygium alternifolium
Time (hr)
Time (hr)
Journal
of
Threatened Taxa | www.threatenedtaxa.org | 26 August 2014 | 6(9): 6153–6171
Reproductive ecology of Syzygium alternifolium
Raju et al.
6164
as S. tierneyanum (Lack & Kevan 1984), S. cuminii (Reddi
& Rangaiah 1999–2000), S. luehmannii (Sanewski 2010),
S. sayeri (Williams & Adam 2010) and S. aqeum (Tarai
& Kundu 2008). S. alternifolium is also a mass bloomer
and it flowers during dry season. The flowering occurs
after partial leaf shedding and leaf flushing occurs after
the completion of flowering. This finding does not
agree with the observation made by Mohan & Lakshmi
Order/Family
Scientific Name
Common Name
Forage
collected
Visiting status
Hymenoptera
Apidae
Apis dorsata F.
Rock bee
N
Regular
A. cerana F.
Indian honey bee
N
Regular
A. florea F.
Dwarf honey bee
N
Regular
Trigona iridipennis Smith
Stingless bee
N + P
Regular
Amegilla sp.
Digger bee
N
Regular
Crabronidae
Stizus sp.
Sand wasp
N
Regular
Vespidae
Eumenes sp.
Potter wasp
N
Regular
Vespa cincta F.
Yellow-banded wasp
N
Regular
V. orientalis L.
Oriental Hornet
N
Regular
Diptera
Calliphoridae
Chrysomya megacephala F.
Oriental latrine fly
N
Occasional
Syrphidae
Helophilus sp.
Hoverfly
N
Occasional
Coleoptera
Scarabaeidae
Popillia impressipyga Ohaus
--
Flower parts
Resident
Unidentified sp.
--
N
Occasional
Lepidoptera
Papilionidae
Papilio polytes L.
Common Mormon
N
Regular
Graphium nomius Esper
Spot Swordtail
N
Regular
Pieridae
Catopsilia pyranthe L.
Mottled Emigrant
N
Regular
Catopsilia pomona F.
Common Emigrant
N
Regular
Nymphalidae
Euploea core Cramer
Common Indian Crow
N
Regular
Tirumala limniace Cramer
Blue Tiger
N
Regular
Precis iphita Cramer
Chocolate Pansy
N
Regular
Junonia lemonias L.
Lemon Pansy
N
Regular
Melanitis leda L.
Common Evening Brown
N
Regular
Danaus genutia Cramer
Common Tiger
N
Regular
Neptis hylas L.
Common Sailer
N
Regular
Mycalesis perseus F.
Common Bushbrown
N
Regular
Moduza procris Cramer
The Commander
N
Regular
Lycaenidae
Arhopala amantes Hewitson
Large Oakblue
N
Regular
Hesperiidae
Pseudocoladenia indrani F.
Tricolour Pied Flat
N
Regular
Borbo cinnara Wallace
Rice Swift
N
Regular
Hasora chromus Cramer
Common Banded Awl
N
Regular
Celaenorrhinus ambareesa Moore
Common Spotted Flat
N
Regular
Sphingidae
Cephonodes hylas L.
Pellucid Hawk Moth
N
Regular
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