Comparative study of reproductive structures in coniferales.pdf

Comparative study of reproductive structures in coniferales.pdf

1. Comparative study of
reproductive
structures in
coniferales
Submitted to
Miss.MerinAlice George
St.Teresa’scollege,EKM
Submitted by
AncyVarghese
I MSc Botany
St.Teresa’scollege, EKM

2. General account on cones of coniferales
•Gymnosperms –naked seed
•Ovules are borne unprotected on
surface of megasporophyllsor arranged as cones
•No fruit formation.
•Cones are unisexual.
•Male cones –simple & contain many scale like microsporophylls
•Female cone consist of many sterile bract scales and fertile ovuliferousscales; in
the axils of ovuliferousscales ovules are present.

3. Pinus

4. Male cone –Female cone
•Develop in clusters; 15-140 in a cluster.
•Ovoid in shape.
•Microsporophyll –small ,
membranous, brown colouredstalked
structure with an apophysis.
•Either solitary or in groups.
•Develop at axils of scaly leaves.
•Ovoid structure when young, becomes
elongated or cylindrical at maturity.
•Ovuliferousand bract scales present.

5. Cupressus

6. Male cone –Female cone
•Cylindrical, yellow when ripe
•Erect , sub-sessile and terminal.
•6-8 pairs of microsporophylls
arranged in cyclic disposition
•Brownish green , globose
•Ripening into brown –grey woody
cones
•Ovoid , axillary
•Each ovuliferousscale contains 3-7
ovules.

7. Podocarpus

8. Male cone –Female cone
•Axillary ;
•Male cones have several spirally
arranged microsporophyllseach
terminating in a triangular shaped
upward projection
•Each pollen develops into male
gametophyte
•Highly reduced , unstrobiloid
•Axillary at the apex of fertile
branch
•Seed is represented only in the
form of a swollen fleshy
receptacle with a terminal ovule

9. Taxus

10. Male cone –Female cone
•Yellowish, globose, stalked
•Developed at axils of foliage
leaves
•Some of the bracts towards the
tip of strobilus are replaced by
stamens
•Highly reduced, hardly appear as
cones
•Arise in the axils of leaves
•A ring like outgrowth –aril –
covers entire ovule

11. Ginkgo

12. Male cone –Female cone
•Axillary, not compact
•Catkin like structure
•Contains several microsporophylls
arranged loosely on a central axis
•Reduced structures
•Develop in groups in the axils of
leaves
•Each branch bears a single ovule
•A fleshy cup-like structure –collar
–present

13. Cryptomeria

14. Male cone -Female cone
•Occur several together or in
solitary
•Ovoid or oblong in shape
•Yellow or bright brown coloured
•1-6 pollen sacs per male cone
scale
•9-30 mm long
•Globose, woody
•Female cone scales are
arranged spirally
•Tip acute with small or large
umbo

15. Agathis

16. Male cone -Female cone
•Seen at lower branches of trees
•Cylindrical
•Microsporophyllsare spirally
arranged around axis, with small
stalk, peltatehead
•Large, solitary, stalked and sub-
globose
•Seen at upper part of trees
•Broader than long
•On central axis megasporophylls
are spirally arranged