Category: Biology Second Paper Lecture Sheet

A type of bud is produced from the base of the stem of Cycas. Cutting the bud and transplanting it into a full grown Cycas tree. Besides, bulbils are formed from the axis of the leaf. Bulbils produce new seedlings.

1. Organ reproduction: A type of bud is produced from the base of the stem of Cycas. Cutting the bud and transplanting it into a full grown Cycas tree. Besides, bulbils are formed from the axis of the leaf. Bulbils produce new seedlings.
2. Sexual reproduction: Cycas are dioecious and unisexual plants. Their male plants produce spores or microspores and female plants produce spores or megaspores. Microspores are located in microsporophylls and megaspores are located in megasporophylls. The microsporophylls together form the strobilus or staminate or cone. Megasporophylls form a crown without forming a strobilus.
(i) Microsporophyll: Cycas plants have spike-shaped strobilus at the apex (50 cm). Stamen strobilus is surrounded by numerous sporangia or microsporophylls. Microsporophylls are 3-5 cm long and 12-23 mm wide. The microsporophylls are spirally and densely arranged. It is flat, thick and scaly. Its base is narrow and its tip is wide. Anteriorly there is a triangular apophysis. Each microsporophyll contains numerous sporangia. 2-5 sporangia together form a sorus. Inside the sporangium is the spore mother cell. Each spore mother cell divides by the process of meiosis to produce spores or microspores. Microspores produce sperm. Spermatozoa of Cycas are Latim-like, multi-flagellated and the largest in the plant kingdom.
(ii) Megasporophyll: The megasporophylls of Cycas are leaf-like, hairy and brown in colour. Together they form the crown. The upper part of megasporophyll is called pinnule. At its base are 2-4 pairs of large and red ovules. The megasporophyll with the ovule looks like a snake’s hood. It is called Sarpamani (sold as Sarpamani in the market). Inside the ovum are the female cells. Spore mother cells divide by meiosis to produce spores or megaspores. Archegonia are formed from the female sperm. Ovules develop inside the archegonium. Archegonium is the original characteristic of Cycus.
(iii) Fertilization: The spores of Cycas are airborne and fall on the ovules of the female plant. Anthers or pollen tubes are formed from the protozoa. Sperm are produced inside the anther. Sperm and egg unite to form zygote. Zygote develops into seed. The seeds are juicy, orange or red in color. The seed germinates and produces a new plant.
The ovules are arranged on both sides at the base of megasporophyll of Cycus. The megasporophyll with the ovule looks like a snake’s hood. It is called Sarpamani. In various places, snake gems are sold as medicine for all diseases. Actually it has no medicinal properties. As a result common people are being cheated or deprived.

1. The main plant is the sporophyte.
2. The body can be divided into roots, stems and leaves.
3. Leaves are large, green, pinnately compound.
4. Young leaves have sarcinate vernation or whorls.
5. Their spermatozoa are multi-flagellated and motile.
6. They are heterosporous or uninucleate.
7. Heteromorphic or unequally shaped genera are seen.

Cycas are plants of the Cycadales class. Plants of the Cycadales class are called Cycads. Cycads were widespread throughout the world during the Mesozoic Era. Later they disappeared. Today they are found as fossils. 100 species of 9 genera including Cycas in the Cycadales class are still alive on Earth. Characteristics of present-day living Cycas are found to closely match those of fossil Cycads of the past. Hence Cycas are called living fossils.

If the characteristics of a living plant of the present time are matched with the characteristics of a fossil plant of the past, it is called a living fossil. Cycas is a living fossil.

Cycas have two types of leaves at the top of the stem. Leaflets and invoices.
(i) Leaves or Compound: Leaves are simple, green, smooth, large and pinnately compound. It is spirally arranged at the tip of the stem and forms a crown-like structure. Rackets contain 50-100 pairs or 100-200 leaflets. The leaves are obtuse, thick and leathery. Its length is 1.0-2.7 m. The mature leaves have a midvein, the veins and subveins are indistinct. Immature and young leaves are coiled like ferns. This condition is called sarcinate vernation.
(ii) Sepals: Sepals are small and covered with brown hairs. It is alternately furnished with foliage. It covers the bud of compound leaves.
Cycas leaves have some similarities with the leaves of palm plants and ferns. Hence Cycas is called pumpfern.

The stem of Cycas is straight, long, sessile, stout and cylindrical. It grows up to 8-14 feet tall. Some species are even taller. When the apex of the stem breaks, the stem becomes branched. It is covered with temporary leaves like armor. It has a permanent leaf scar.

The main root of Cycas is transient. Abdominal roots are formed after the main root is destroyed. Abdominal roots grow underground. Some parts of the adventitious root emerge above the soil and bifurcate to form branches. Above ground these root bacteria are attacked by Nostoc, Anabaena etc. The normal shape of these affected roots changes and becomes deformed. Because the distorted shape of the root resembles that of sea coral or coral, they are called coralloid roots or coral roots or root tubercles. The part of the cortex of the coralloid root where Nostoc and Anabina reside is called the algal layer.

1. Root: The main root of Cycas is transient. Abdominal roots are formed after the main root is destroyed. Abdominal roots grow underground. Some parts of the adventitious root emerge above the soil and bifurcate to form branches. Above ground these root bacteria are attacked by Nostoc, Anabaena etc. The normal shape of these affected roots changes and becomes deformed. Because the distorted shape of the root resembles that of sea coral or coral, they are called coralloid roots or coral roots or root tubercles. The part of the cortex of the coralloid root where Nostoc and Anabina reside is called the algal layer.
2. Stem: The stem of Cycas is straight, long, sessile, stout and cylindrical. It grows up to 8-14 feet tall. Some species are even taller. When the apex of the stem breaks, the stem becomes branched. It is covered with temporary leaves like armor. It has a permanent leaf scar.
3. Leaves: Cycas have two types of leaves at the top of the stem. Leaflets and invoices.
(i) Leaves or Compound: Leaves are simple, green, smooth, large and pinnately compound. It is spirally arranged at the tip of the stem and forms a crown-like structure. Rackets contain 50-100 pairs or 100-200 leaflets. The leaves are obtuse, thick and leathery. Its length is 1.0-2.7 m. The mature leaves have a midvein, the veins and subveins are indistinct. Immature and young leaves are coiled like ferns. This condition is called sarcinate vernation.
(ii) Sepals: Sepals are small and covered with brown hairs. It is alternately furnished with foliage. It covers the bud of compound leaves.
Cycas leaves have some similarities with the leaves of palm plants and ferns. Hence Cycas is called pumpfern.

1. Cycas are sporophyte plants. Its body can be divided into roots, stems and leaves.
2. They are erect palm-like plants.
3. They have brown hairy bracts and green foliage.
4. The green leaves are large, pinnately compound and spirally arranged.
5. Young leaves have sarcinate vernation or whorls.
6. Their leaves contain transfusion tissue.
7. Stems are straight, sessile, stout, cylindrical and with persistent petioles.
8. They have seeds, no fruit and the seeds are naked.
9. Germs form strobilus.
10. Their ovules are large, unencapsulated and located in the endosperm.
11. They are heterosporic or uninucleate.
12. They are air pollinated. That is, pollination takes place through air.
13. They have coralloid roots.
14. Their spermatozoa are the largest, Latim-like, multi-flagellated and motile. Dr. Siddique Publications
15. Their sexual reproduction is ogamous in nature.
16. Their embryos are created.
17. They are archegonoids.