''Cycas micronesica'' is a species of
cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...
found on the island of
Yap
Yap ( yap, Waqaab) traditionally refers to an island group located in the Caroline Islands of the western Pacific Ocean, a part of Yap State. The name "Yap" in recent years has come to also refer to the state within the Federated States of Micr ...
in
Micronesia
Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...
, the
Marianas islands of
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
and
Rota, and
The Republic of Palau. It is commonly known as federico nut or ''fadang'' in
Chamorro Chamorro may refer to:
* Chamorro people, the indigenous people of the Mariana Islands in the Western Pacific
* Chamorro language, an Austronesian language indigenous to The Marianas
* Chamorro Time Zone, the time zone of Guam and the Northern Mar ...
. The species, previously lumped with ''
Cycas rumphii
''Cycas rumphii'', commonly known as queen sago or the queen sago palm, is a dioecious gymnosperm, a species of cycad in the genus ''Cycas'' native to Indonesia, New Guinea and Christmas Island. Although palm-like in appearance, it is not a pal ...
'' and ''
Cycas circinalis
''Cycas circinalis'', also known as the queen sago, is a species of cycad known in the wild only from southern India. ''Cycas circinalis'' is the only gymnosperm species found among native Sri Lankan flora.
Taxonomy
''C. circinallis'' is native ...
'', was described in 1994 by
Ken Hill.
Paleoecological studies have determined that ''C. micronesica'' has been present on the island of
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
for about 9,000 years. It is linked with
Lytico-Bodig disease
Lytico-bodig (also Lytigo-bodig) disease, Guam disease, or amyotrophic lateral sclerosis-parkinsonism-dementia (ALS-PDC) is a neurodegenerative disease of uncertain etiology endemic to the Chamorro people of the island of Guam in Micronesia. ''Ly ...
, a condition similar to
amyotrophic lateral sclerosis (ALS), due to the
neurotoxin BMAA
β-Methylamino--alanine, or BMAA, is a non-proteinogenic amino acid produced by cyanobacteria. BMAA is a neurotoxin and its potential role in various neurodegenerative disorders is the subject of scientific research.
Structure and properti ...
found in its seeds, which were a traditional food source on
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
until the 1960s. The neurotoxin is present due to its symbiosis with
cyanobacteria.
Description
''Cycas'' ''micronesica'' is a medium-sized tree most commonly 2–5 meters tall but can reach heights up to 15 meters. The tree has a straight palm like trunk ringed with frond scars.
Leaves
Leaves are 140–180 cm long, flat in section (opposing pinnae inserted at 180 degrees on rhachis), with 130 -150 pinnae, terminated by a spine c. 4mm long; petiole usually glabrous, usually unarmed, rarely
spinescent for up to 20% of length, 35 – 45 cm long; median pinnae at 70-80 degrees to rachis, 240 – 280 mm long, 16 –17 mm wide, 0.35 - 0.45 mm thick, glabrous, dull green or slightly bluish-green when developing, becoming glossy mid-green at maturity, flat in section with slightly recurved margins, strongly discolorous, decurrent for 7–10 mm, narrowed to 5.0-6.0 mm at base, 17 – 20 mm apart on rhachis apex attenuate; midrib not sharply raised, more or less equally prominent above and below, 1.2 -1.5 mm wide.
Reproductive organs
Like all
cycads
Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...
, ''Cycas'' ''micronesica'' are
dioecious. Females possess clusters of
ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the '' integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the ...
s situated on modified leaves called
megasporophylls. Male reproductive structures consist of modified leaves called
microsporophylls, but each modified leaf has small, compact pollen sacks attached to their lower surface. There has been documentation of the symbiotic relationship the Guamanian ''C. micronesica'' with
Anatrachyntis sp., which depends on male cones (
microsporangia
Microsporangia are sporangia that produce microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fe ...
) for
oviposition and recruitment in return for pollinating the species.
The microsporangiate cones are pale fawn to pale orange-brown, narrowly ovoid, 30–50 cm long, 8–10 cm in diameter.
Microsporophyll lamina are 35–45 mm long, 20–25 mm wide; fertile zone 25–35 mm long; sterile apex 7–10 mm long, not recurved, apical spine somewhat reduced, broad, sharply upturned, 2 mm long.
Megasporophylls 27–33 cm long, grey- and orange-tomentose, with 2-6 ovules, lamina 45–55 mm wide, broadly ovate to elliptical, regularly dentate with 16-20 lateral spines, apical spine 8–15 mm long, lateral spines 2–6 mm long. Seeds flatten to ovoid, green becoming orange, not pruinose, 50–60 mm long, 45–50 mm in diameter;
sarcotesta
The sarcotesta is a fleshy seedcoat, a type of testa. Examples of seeds with a sarcotesta are pomegranate and some cycad seeds. The sarcotesta of pomegranate seeds consists of epidermal cells derived from the integument
In biology, an integu ...
3–6 mm thick.
Conservation
''Cycas micronesica'' is threatened by a combination of introduced species throughout the islands of
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
and
Rota. The most notable pest is the
diaspidid scale ''
Aulacaspis yasumatsui
''Aulacaspis yasumatsui'', or cycad aulacaspis scale (CAS), is a scale insect species in the genus '' Aulacaspis'' that feeds on cycad species such as ''Cycas revoluta''Aulacaspis yasumatsui (Hemiptera: Sternorrhyncha: Diaspididae), a Scale Inse ...
'', which was first recognized in
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
in December 2003. Other threats include Cycad Blue Butterfly, the longhorn beetle (''
Dihammus marianarum'') which causes stem damage, the alien invasive snail ''Satsuma mercatorius'' which feeds on young leaflets, and habitat loss due to the growing human population.
Prior to the invasion of ''
Aulacaspis yasumatsu'', it was one of the most abundant plants in Guam's forests. Plant mortality was so rapid that the species was Red Listed as Endangered in 2006, only three years after the devastating invasions began . Population counts in northwest Guam has declined from 686 individuals in early 2004 (before ''
Aulacaspis yasumatsui
''Aulacaspis yasumatsui'', or cycad aulacaspis scale (CAS), is a scale insect species in the genus '' Aulacaspis'' that feeds on cycad species such as ''Cycas revoluta''Aulacaspis yasumatsui (Hemiptera: Sternorrhyncha: Diaspididae), a Scale Inse ...
'' reached this habitat) to 87 individuals in January 2007.
In 2004, ''
Rhyzobius lophanthae'' was employed on
Guam
Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
as a biological pest control and has lessened the population decline. However, they were ineffective on protecting cycad seedlings from ''
Aulacaspis yasumatsui
''Aulacaspis yasumatsui'', or cycad aulacaspis scale (CAS), is a scale insect species in the genus '' Aulacaspis'' that feeds on cycad species such as ''Cycas revoluta''Aulacaspis yasumatsui (Hemiptera: Sternorrhyncha: Diaspididae), a Scale Inse ...
'' predation, as lack of seed vigor is one of the major factors contributing to C. micronesica decline.
[Marler, T., Miller, R., & Moore, A. (2013). Vertical Stratification of Predation on Aulacaspis yasumatsui Infesting Cycas micronesica Seedlings. ''HortScience,'' ''48''(1), 60-62.]
References
External links
The Cycad Pages – ''Cycas micronesica''Plants_of_Guam_[Botanical_University_of_Guam_College_of_Natural_Arts_and_Sciences.html" ;"title="otanical">
Plants of Guam otanical">Plants_of_Guam_[Botanical
_University_of_Guam_College_of_Natural_Arts_and_Sciences_
Flickr:_Plants_of_Guam_by_Lauren_Gutierrez_-_Cycas_micronesica_K.D._Hill
Guam_Plant_Extinction_Prevention_Program
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University of Guam College of Natural Arts and Sciences">otanical">Plants of Guam Flickr:_Plants_of_Guam_by_Lauren_Gutierrez_-_Cycas_micronesica_K.D._Hill
Guam_Plant_Extinction_Prevention_Program
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Flickr: Plants of Guam by Lauren Gutierrez - Cycas micronesica K.D. Hill
Guam Plant Extinction Prevention Program
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Flora_of_the_Northwestern_Pacific
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Flora of the Northwestern Pacific
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Flora of the Northwestern Pacific
Plants described in 1994