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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]
However, unlike these other groups, ovules are produced on cone scales, which are modified shoots rather than sporophylls. Some plants do not produce sporophylls. Sporangia are produced directly on stems. Psilotum has been interpreted as producing sporangia (fused in a synangium) on the terminus of a stem.
The individual plates of a cone are known as scales. In conifers where the cone develops over more than one year (such as pines), the first year's growth of a seed scale on the cone, showing up as a protuberance at the end of the two-year-old scale, is called an umbo, while the second year's growth is called the apophysis. [1]
The scales or microsporophyll, are arranged cylindrically around the pin axis. Their shape is triangular to rhomboid. Each microsporophyll forms about 150 pollen sacs, which are attached in groups of 3-6 at the bottom. At maturity, the pin axis extends and the scales are lifted apart and release the pollen.
The female cones are also stalked and can remain on the plant for more than a year. The female microsporophyll are more leaf-like than those of other cycads, the greatest similarity to those of the genus Cycas. The scales are flattened at the top, widened and bent up. Each sporophyll carries two, rarely three, ovules.
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 [1] or Dioon purpusii (Purpus' cycad). Other common names include the cycad scale, the sago palm scale, [2] and the Asian cycad scale. [3] This is a serious pest of cycads which can kill ...
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The microsporangium is carried by microsporophyll (modified leaf) and seeds are carried by ovuliferous scales in the male and female cones respectively. [2] [34] The exception is the females in the cycad genus Cycas, which form a loose structure called megasporophylls instead of cones. [35]