Cycads

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Cycas
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Morphology
Scientific name Cycas
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About Cycads
Found in the Jurassic period of the Mesozoic
era. (250-145 million years ago)
They can grow in Subtropical and Tropical
climates.
They grow in any type of soil mostly moist
habitats.
185 different species of Cycads
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Gymnosperms
Four major living groups. Cycads (Cycadophyta),
Welwitschia group (Gnetophyta), Ginkgo, the
Maiden Hair Tree (Ginkgophyta), and the
conifers (Pinophyta) .

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Cycads
Cycas bougainvilleana
Cycads resemble palms or tree-ferns in overall
appearance but differ greatly in detailed
structure and reproductive behaviour. Cycads are
dioecious (i.e. male and female reproductive
structures are borne on separate plants), and
reproduction is by seeds produced on open
carpophylls or seed-bearing leaves. Although
technically woody plants, unlike other woody
plants, cycads have a thick, soft stem or trunk
made up of mostly storage tissue with very little
true wood. The living cycads include about 250
species, with 11 genera in 3 families.
Microcycas calocoma Photo Dennis Stevenson
Female cone
Cuban species
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Cycas-Circinate vernation of young foliage leaf
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Cycas-Coralloid root
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T.S. Leaflet of Cycas
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Cycas- T.S. Microsporophyll
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Cycas- Young ovule
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Cycas- Megasporophyll with young ovule
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Cycas- Mature ovule
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Cycas- Mature ovule
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The microspores develop into pollen grains.
Male Gametophyte
Female Gametophyte
This female gametophyte is developed from the
megaspores.
the dominant lifecycle stage is the sporophyte.
Sporophyte relies on gametophyte for a period of
time to develop into a seed.
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Life Cycle of the Cycads
gynostrobilus grows a pollen tube, sperm cell
swims through pollen tube using its tail, or
flagella. (haploid )This fertilizes the egg and
it becomes a zygote. (Dipoid)
Male reproductive stucture, pollen is dispersed
by wind or insects to female reproductive
structure. (haploid)
Zygote develops into an embryo then a seed is
developed in a coat that originates from the
ovary. (diploid)
Development of the microspores and megaspores
through meiosis (haploid)
Then the tree grows! (diploid)
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Economic and health benefits of Cycads

• Some cycads are poisonous as a result there are
  not many medical benefits
• These are also very close to extinction
• If prepared correctly they can be eaten
• The nuts contain a nerve toxin
• Consumption of the starch derived from cycads is
  a factor in the development of Lytico-Bodig
  disease, a disease symptoms similar to
  Parkinson's and ALS.
• But they look kinda pretty!!

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Thank You