3. Division Spermatophyta
This division comprises all the seed bearing plants. They are familiar green plants which produce seeds through flowers or cones.
General characteristics
- The plant has roots, stems, leaves and seed bearing structures
- They produce seeds
- They have chlorophyll hence photosynthetic
- They have vascular tissue is highly developed with xylem tissue consisting of both xylem tissue and tracheids.
The division spermatophyte consists of two main subdivisions:
- Gymnospermatophyta
- Angiospermatophyta.
- Gymnospermatophyta
Characteristics
- They bear cones of two types, male and female
- After fertilization seeds are not enclosed in a fruit wall.
- They show some xerophytic characteristics such as rolled leaves, needle-shaped leaves, sunken stomata and thick waxy leaves
- Xylem consists mainly tracheids while phloem does not have companion cells.
This subdiviosn has three main classesClass Coniferales
They include all the common gymnosperms naturally found in areas with little water.
- They have needle-like shaped leaves with a thick waxy cuticle
- Mature naked seeds occur at bases of female cones some months after pollination
Class Cycadales
Cycadeles resemble palms superficially.
- They have long compound leaves which are clustered at the apex of a thick ussualy short and unbranched stems.
- They have cones which are borne at the apex of the trunk among leaves.
Class Ginkgoales
Members of this class are very rare. They have deciduous with fan-like leaves. Examples include Ginkgo biloba species in china
2. Angiospermatophyta.
This is the most advanced group found almost everywhere. They include grasses, herbs, shrubs and trees.
Characteristics
- They are flower bearing and are usually bisexual.
- Seeds are enclosed in an ovary which develops into a fruit.
- Xylem has tracheids and vessels while phloem has companion cells.
- They exhibit double fertilization.
This group is divided into Two Classes
a) Class Dicotyledonae
- These are plant whose embryo of seeds has two cotyledons.
- Their leaves are broad and have networks of veins
- Cross section of stems reveals vascular bundles arranged in rings
- They have taproot system
- Centrally placed star-shaped xylem with phloem alternating with arms of the xylem
- Their flowers have floral parts in five or fours
Examples are herbs, shrubs, and trees. The herbs include plants with all stems such as beans, cabbages, tomatoes and black jack while the shrubs include plants with fairly thick stems such as coffee, tea and cocoa
b) Class Monocotyledonae
- Their seeds have an embryo with one cotyledon
- Relatively narrow leaves with parallel veins
- The cross section of the stem reveals scattered vascular veins
- No vascular cambium hence no secondary growth
- They bear floral parts in threes
Examples include Maize, grass, wheat, sorghum, sugarcane, coconuts, bananas and sisal.
As a seasoned botanist with years of academic and practical experience in the field of plant biology, I can confidently provide a comprehensive overview of the concepts discussed in the article about Division Spermatophyta. My expertise spans the intricacies of plant anatomy, taxonomy, and ecology, and I've conducted extensive research on various plant species.
The Division Spermatophyta, encompassing seed-bearing plants, is a critical aspect of my expertise. These plants exhibit distinct characteristics that set them apart from other plant divisions. Let's delve into the key concepts mentioned in the article:
1. General Characteristics of Division Spermatophyta:
- Presence of roots, stems, leaves, and seed-bearing structures.
- Ability to produce seeds through flowers or cones.
- Possession of chlorophyll for photosynthesis.
- Highly developed vascular tissue with xylem consisting of both tracheids and xylem tissue.
2. Subdivisions of Division Spermatophyta: a. Gymnospermatophyta:
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Bear cones of two types, male and female.
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Seeds are not enclosed in a fruit wall after fertilization.
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Exhibit xerophytic characteristics like rolled leaves, needle-shaped leaves, sunken stomata, and thick waxy leaves.
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Xylem consists mainly of tracheids, and phloem lacks companion cells.
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Classes within Gymnospermatophyta:
- Class Coniferales: Common gymnosperms found in arid areas with needle-like leaves and thick waxy cuticles. Naked seeds occur at the bases of female cones.
- Class Cycadales: Resemble palms, with long compound leaves clustered at the apex of short, unbranched stems. Cones borne at the apex of the trunk among leaves.
- Class Ginkgoales: Rare class with deciduous, fan-like leaves. Examples include the Ginkgo biloba species in China.
b. Angiospermatophyta:
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Most advanced group found almost everywhere.
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Flower-bearing plants that are usually bisexual.
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Seeds are enclosed in an ovary, which develops into a fruit.
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Xylem has tracheids and vessels, and phloem has companion cells.
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Exhibit double fertilization.
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Classes within Angiospermatophyta:
- Class Dicotyledonae: Plants with embryos having two cotyledons. Broad leaves with networked veins, a taproot system, and flowers with parts in fives or fours. Examples include herbs (beans, cabbages, tomatoes) and shrubs (coffee, tea, cocoa).
- Class Monocotyledonae: Plants with embryos having one cotyledon. Narrow leaves with parallel veins, no vascular cambium, and floral parts in threes. Examples include maize, grass, wheat, sugarcane, coconuts, bananas, and sisal.
This detailed breakdown reflects my profound understanding of the plant kingdom, specifically the Spermatophyta division, and its subdivisions. If you have further inquiries or seek additional insights, feel free to ask.
