This document provides an overview of gymnosperms, including their general characters, classification, and examples. It discusses how gymnosperms are woody, vascular plants whose seeds are not enclosed in fruits. They are classified into 5 orders - Cycadales, Coniferales, Ephadrales, Gnetales, and Ginkgoales. Examples like cycas, conifers, ephedra, gnetum, and ginkgo biloba are described. The classification system proposed by David Bierhost in 1971 is outlined.

1. GENERAL CHARACTERS AND
CLASSIFICATION OF GYMNOSPERMS
Presented By:-
Vaghela Bhavubha A.
MSc Sem:-1 (BOTANY)
PAPER:- CBO-402
DEPT. OF LIFE SCIENCES,
HNGU, PATAN

2. CONTENTS
Introduction
General Characters Of Gymnosperms
Classification (Birehost) Of Gymnosperms
References

3. INTRODUCTIONINTRODUCTION
Gymnosperm are a group of vascularGymnosperm are a group of vascular
plants whose seeds are not enclosed by aplants whose seeds are not enclosed by a
ripend ovary (fruits).ripend ovary (fruits).
 The seeds of many gymnospems (literallyThe seeds of many gymnospems (literally
“naked seed”) are borne in cones and are not“naked seed”) are borne in cones and are not
visible.visible.
Currently about 60-70 genera are recognizedCurrently about 60-70 genera are recognized
,with a total of 700-800 species.,with a total of 700-800 species.

4. General Characters Of
Gymnosperms
•The Gymnosperms are woody, perennial
forms. Plants are either trees or shrubs. There
are mostly evergreen trees, though a few
species are deciduous i.e., They are addapted
to xerophytic habit.

5. gymnosperm

6. • They possess a well developed tap root system
which provides a better anchorage and
facilitates absorption of water.
• The leaves may be one type only or may be of
two types (dimorphic) scale leaves and foliage
leaves. Foliage leaves are evergreen and may
show a cyclic arrangement (cupressus) or
spiral arrangement (pinus). They may be
simple or compound.

7. • The roots have radial vascular bundle with
exarach xylem.It may be diarch, triarch or
tetrarch.
• The stem has conjoint and collateral vascular
bundles with endarch xylem.The vascular
bundles are arranged in a ring as in dicot
stems.
• The xylem except gnetales consists
exclusively of pitted tracheids.

8. • The phloem is devoid of companion cells.
• The reproductive organs, except female
reproductive organs of cycas, are aggregated
to form strobili or cones and are made up of
aggregated to form strobilli are usually either
male (microsporangiate) or female
(megasporangiate) i.e., unisexual. Rarely they
are bisporangiate i.e., bisexual.

9. • The megasporangia (ovules) are borne on the
surface of the megasporophyll.
• The female gametophyte consists of a well
developed vegetative tissue, endosperm.It has
two or more archegonia.

10. • The male cones are short lived. The
microsporangia are found on the lower or
abaxias side of the microsporophyll.They are
numerous and form sori in cycas. In pinus only
two microsporangia are found on each
microsporophyll.
• The male gametophyte is reduced and contains
one (cycas) or two (pinus) prothallial cells.

11. • The male and female gametophytes are
reduced and are dependent upon the
sporophyte. They develop within the tissues of
the sporophyte.
• The pollen tube grows through the female
gametophyte and reaches the archegonium.

12. • The Oospore developes into un embryo.
Polyembryony is common in some types.
• The seed contains two or more cotyledons and
on germination gives rise to the plant body.

13. CLASSIFICATION OF
GYMNOSPERMS
• Many systems of classification of the
gymnosperms have been proposed up to the
present day.
• David bierhost (1971) proposed the following
classification.

14. (1) Cycadales
• The order includes both living and extinct
forms that originated in the upper triassic
period of the early mesozoic era.
• Most diverse during age of dinosaurs.
• Only 100 living species.
• Palmlike appearance.
• Seed bearing and pollen bearing cones on
different plants.

15. cycas

16. (2) Coniferales
• The living conifers include largest number of
living species.
• Distributed mainly in temprate regions or in
the mountains of the topics.
• Woody trees or shrubs.
• Most of evergreen.
• Bear seeds on exposed cone scales.
• Most produce woody cones.

17. conifers

18. (3) Ephadrales
• The secondary wood contains vessels.
• The flowers are arranged in compound strobilli
and are unisexual and usually dioecious.
• The ovules are orthotropous.

19. Ephedra

20. (4) Gnetales
• The sporophytes may be shrubs, trees or even
woody climber.
• The leaves may be spirally arranged, opposite
or even whorled.
• The secondary wood has vassels.
• The reproductive organs are organised into
compound strobili or inflorescences.

21. Gnetum

22. (5) Ginkgoales
• Diverse during age of dinosaurs.
• One surviving species – Ginkgo Biloba.
• Deciduous trees are male or female.
• Seeds are completely exposed.

23. ginkgoales

24. References
• A Textbook Of Gymnosperm
-R.M. johri , Sneh Lata, Kavita Tyagi
• www.slideshare.net