Cycas micronesica

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Cycas micronesica
Cycas micronesica photo courtesy A. Gawel (15391498081).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Family: Cycadaceae
Genus: Cycas
Species:
C. micronesica
Binomial name
Cycas micronesica
K.D. Hill, 1994

Cycas micronesica is a species of cycad found on the island of Yap in Micronesia, the Mariana islands of Guam and Rota, and The Republic of Palau. It is commonly known as federico nut or fadang in Chamorro. The species, previously lumped with Cycas rumphii and Cycas circinalis , was described as a unique species in 1994 by Ken Hill. [2] Paleoecological studies have determined that Cycas micronesica has been present on the island of Guam for about 9,000 years. [3] It has been implicated as a factor in Lytico-Bodig disease, a condition similar to amyotrophic lateral sclerosis (ALS), due to the presence of the neurotoxin BMAA found in its seeds. Seeds were a traditional food source on Guam until the 1960s. [4] The neurotoxin is present due to a symbiosis with cyanobacteria. [5] [6]

Contents

Description

Stem with ringed leaf scars Cycas micronesica trunk, Guam National Wildlife Refuge.jpg
Stem with ringed leaf scars

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. [7]

Cycas micronesica (fadang) emergent leaves unfurling. Dededo, Guam.jpg

Leaves

Leaves are 140–180 cm long, flat in section (opposing pinnae inserted at 180 degrees on rachis), with 130 -150 pinnae, terminated by a spine approximately 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 rachis apex attenuate; midrib not sharply raised, more or less equally prominent above and below, 1.2 -1.5 mm wide. [8]

Reproductive organs

Like all cycads, Cycas micronesica are dioecious. Females possess clusters of ovules 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. [9] There has been documentation of a symbiotic relationship between Cycas micronesica and an Anatrachyntis moth species on Guam, which depends on male cones (microsporangia) for oviposition and recruitment in return for pollinating the female cone.

Female cones (megasporophylls)

The female cones are pale fawn to pale orange-brown, narrowly ovoid, 30–50 cm long, 8–10 cm in diameter. 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 3–6 mm thick. [8]

Male cones (microsporophylls)

Microsporophyll laminae 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.

Conservation

Male cone and leaves infested with cycad aulacaspis scale (CAS) Infested cone of c micronesica.jpg
Male cone and leaves infested with cycad aulacaspis scale (CAS)

Cycas micronesica is threatened by a combination of introduced species throughout the islands of Guam and Rota. The most notable pest is the diaspidid scale, Aulacaspis yasumatsui , which was first recognized on Guam in December 2003. [10] Other threats include cycad blue butterfly ( Luthrodes pandava ); the longhorn beetle ( Acalolepta marianarum ), which causes stem damage; the alien invasive snail Satsuma mercatoria, which feeds on young leaflets; and habitat loss due to the growing human population and military activities. [1] Prior to the invasion of Aulacaspis yasumatsui, it was one of the most abundant plants in Guam's forests. [11] Plant mortality was so rapid that the species was listed as Endangered by the IUCN Red List in 2006, only three years after the devastating invasions began. [12] [13] Population counts in northwest Guam had declined from 686 individuals in early 2004 (before Aulacaspis yasumatsui reached this habitat) to 87 individuals in January 2007. [1] Cycas micronesica used to have stable populations across Micronesia, with Guam having the largest. However, the Aulacaspis scale invasion caused an 87% decline in the Guam subpopulation over ten years. [14] In 2004, Rhyzobius lophanthae was introduced on Guam as a biological pest control and has lessened the population decline. However, they were ineffective at protecting cycad seedlings from Aulacaspis yasumatsui predation, as lack of seed vigor is one of the major factors contributing to Cycas micronesica decline. [15] Without effective action against the Aulacaspis scale, the Guam population may become critically endangered.

Threats

The cycad aulacaspis scale (CAS), an invasive species from Southeast Asia, poses a significant threat to Cycas micronesica, resulting in substantial plant mortality. However, the current plant mortality is not solely due to the scale. The introduction of the cycad blue butterfly in 2005 and the intensified damage caused by pre-existing arthropod pests are additional severe threats to the already weakened cycad population. Longhorn beetles, especially Acalolepta marianarum, are responsible for many recent plant deaths due to stem damage. Moreover, the invasive snail Satsuma mercatoria, has only recently been noted to be feeding on young leaflets. This change in herbivore behavior may be a result of the compromised ability of unhealthy cycad plants to synthesize chemicals that deter herbivores. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Sporangium</span> Enclosure in which spores are formed

A sporangium ; pl.: sporangia) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other groups form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in land plants and many fungi, sporangia produce genetically distinct haploid spores by meiosis.

<span class="mw-page-title-main">Conifer cone</span> Reproductive organ on conifers

A conifer cone or pinecone is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers and cycads. The cone of Pinophyta contains the reproductive structures. The woody cone is the female cone, which produces seeds. The male cone, which produces pollen, is usually herbaceous and much less conspicuous even at full maturity. The name "cone" derives from Greek konos, which also gave name to the geometric cone. The individual plates of a cone are known as scales. The umbo of a conifer cone refers, showing up as a protuberance at the end of the two-year-old scale.

<i>Stangeria</i> Monotypic genus of cycads in the family Stangeriaceae

Stangeria eriopus is a cycad endemic to southern Africa. It is the sole species in the genus Stangeria, most closely related to the Australian genus Bowenia, with which it forms the family Stangeriaceae.

<i>Cycas</i> Genus of cycads in the family Cycadaceae

Cycas is a genus of cycad, and the only genus in the family Cycadaceae with all other genera of cycad being divided between the Stangeriaceae and Zamiaceae families. Cycas circinalis, a species endemic to India, was the first cycad species to be described in western literature, and is the type species of the genus.

<i>Cycas revoluta</i> Species of plant

Cycas revoluta is a species of gymnosperm in the family Cycadaceae, native to southern Japan including the Ryukyu Islands. It is one of several species used for the production of sago, as well as an ornamental plant. The sago cycad can be distinguished by a thick coat of fibers on its trunk. The sago cycad is sometimes mistakenly thought to be a palm, although the only similarity between the two is that they look similar and both produce seeds.

<span class="mw-page-title-main">Sporophyll</span>

A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia and thus are called megasporophylls, or microsporangia and are called microsporophylls. The overlap of the prefixes and roots makes these terms a particularly confusing subset of botanical nomenclature.

<i>Dioon</i> Genus of cycads in the family Zamiaceae

Dioon is a genus of cycads in the family Zamiaceae. It is native to Mexico and Central America. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes.

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

<i>Cycas beddomei</i> Species of cycad

Cycas beddomei is a species of cycad in the genus Cycas, native to India, where it is confined to a small area of Andhra Pradesh state in the Tirumala Hills in scrubland and brush covered hills.

Cycas bifida is a species of cycad plant in the genus Cycas, native to southern China, and northern Vietnam.

<i>Cycas circinalis</i> Species of cycad

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.

<i>Macrozamia glaucophylla</i> Species of plant

Macrozamia glaucophylla is a species of cycad from the genus Macrozamia and the family Zamiaceae. Endemic to New South Wales, Australia, this species has features that resembles palms, although both species are taxonomically quite different. The current population trend of Macrozamia glaucophylla is stable with 2,500 to 10,000 mature individuals. The species are found in several habitats including forest and savanna. Ecologically, Macrozamia glaucophylla lives in terrestrial system, a land-based community of organisms where the biotic and abiotic components interact in the given area.

<i>Macrozamia miquelii</i> Species of cycad

Macrozamia miquelii, is a species of cycad in the plant family Zamiaceae. It is endemic to Queensland and New South Wales in Eastern Australia. Located within sclerophyll forests dominated by eucalyptus trees, the cycad grows on nutrient-poor soils. It is recognised within the Zamiaceae family for its, medium height at 1 m, intermediate size of male and female cones and lighter green leaves compared to other cycads within the plant family of Zamiaceae. The seeds have an orange red sarcotesta which attracts fauna consumption, allowing a mutualistic seed dispersal for the cycad. These seeds are also edible for human consumption if prepared correctly to remove the toxins.

<i>Dioon purpusii</i> Species of cycad

Dioon purpusii is a cycad tree endemic to a very small region in Mexico. It is found in Tomellín Canyon and the eastern branches of La Cañada de Cuicatlán.

<i>Cycas rumphii</i> Species of plant

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 palm.

<i>Cycas thouarsii</i> Species of evergreen plant

Cycas thouarsii, the Madagascar cycad, is an evergreen arborescent cycad in the genus Cycas. It is named after the French botanist Louis-Marie Aubert du Petit-Thouars (1758—1831).

<span class="mw-page-title-main">Aulacaspis yasumatsui</span> Species of true bug

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 or Dioon purpusii. Other common names include the cycad scale, the sago palm scale, and the Asian cycad scale. This is a serious pest of cycads which can kill its host plant.

<i>Cycas zeylanica</i> Species of cycad

Cycas zeylanica, common name maha-madu is a plant apparently at present endemic to the Andaman and Nicobar Islands. It was formerly also present in Sri Lanka, but the last remnants of the populations there were destroyed by the tsunami of December 2004. A few trees are cited in Hanguranketha town Adikarigama area.

<i>Encephalartos whitelockii</i> Species of plant

Encephalartos whitelockii is a species of cycad that is native to Uganda.

<i>Cycas inermis</i> Species of cycad

Cycas inermis is a vascular plant belonging to the family Cycadaceae, endemic to central and southern Vietnam. Its name in Vietnamese is Thiên tuế or Tuế lá quyết.

References

  1. 1 2 3 Bösenberg, J.D. (2022). "Cycas micronesica". IUCN Red List of Threatened Species . 2022: e.T61316A68906033. doi: 10.2305/IUCN.UK.2022-1.RLTS.T61316A68906033.en . Retrieved 22 August 2023.
  2. ↑ Hill, K.D. (1994). Cycas micronesica. Australian Systematic Botany7: 554-556.
  3. ↑ Athens, J., & Ward, J. (2004). Holocene vegetation, savanna origins and human settlement of Guam. Records Of The Australian Museum, 15-30.
  4. ↑ Sacks, Oliver. (1996). The Island of the Colour-blind. Pan Macmillan Australia: Sydney. ISBN   0-330-35887-1
  5. ↑ Cox PA, Banack SA, Murch SJ, Rasmussen U, Tien G, Bidigare RR, Metcalf JS, Morrison LF, Codd GA, Bergman B (2005). "Diverse taxa of cyanobacteria produce b-N-methylamino-L-alanine, a neurotoxic amino acid". PNAS. 102 (14): 5074–5078. Bibcode:2005PNAS..102.5074C. doi: 10.1073/pnas.0501526102 . PMC   555964 . PMID   15809446.
  6. ↑ Esterhuizen M, Downing TG (2008). "β-N-methylamino-L-alanine (BMAA) in novel South African cyanobacterial isolates". Ecotoxicology and Environmental Safety. 71 (2): 309–313. doi:10.1016/j.ecoenv.2008.04.010. PMID   18538391.
  7. ↑ Vogt, S., & Williams, L. (2004). Common flora & fauna of the Mariana Islands. Saipan?: S.R. Vogt & L.L. Williams.
  8. 1 2 Hill KD (1994). "The Cycas rumphii complex (Cycadaceae) in New Guinea and the western Pacific". Australian Systematic Botany. 7 (6): 543–567. doi:10.1071/sb9940543. ISSN   1446-5701.
  9. ↑ Willis, K., & McElwain, J. C. (2014). The evolution of plants (2nd ed.). Oxford, United Kingdom; New York: Oxford University Press.
  10. ↑ Terry, Irene; & Marler, Thomas. (2005). Paradise Lost? Tipping the scales against Guam’s Cycas micronesica. The Cycad Newsletter28(3-4): 21-23.
  11. ↑ Donnegan, J., & Pacific Northwest Research Station. (2004). Guam's forest resources, 2002 (Resource bulletin PNW ; 243). Portland, OR: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station.
  12. ↑ Marler, T.E.; Lawrence, J.H. (2012). "Demography of Cycas micronesica on Guam following introduction of the armoured scale Aulacaspis yasumatsui". Journal of Tropical Ecology. 28 (3): 233–242. doi:10.1017/S0266467412000119.
  13. ↑ Marler, T.E. (2010). "Cycad mutualist offers more than pollen transport". American Journal of Botany. 97 (5): 841–845. JSTOR   20700414.
  14. 1 2 "Redlist - Cycas micronesica".
  15. ↑ Marler, T.E.; Miller, R.; Moore, A. (2013). "Vertical Stratification of Predation on Aulacaspis yasumatsui Infesting Cycas micronesica Seedlings". HortScience. 48 (1): 60–62. doi: 10.21273/HORTSCI.48.1.60 .

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