Taxus is an evergreen tree that can grow up to 20 meters tall. It has linear leaves with sharp pointed tips. The leaves are dark green on top and red underneath. Taxus is usually dioecious, reproducing through male and female cones. The male cones contain microsporangia that release pollen. The female cones are highly reduced, containing a few ovules surrounded by a fleshy red aril. The seeds are covered by a three-layered coat. Taxus wood is durable and used for decorative items. Its leaves and seeds are poisonous but also used medicinally to treat various ailments. An anti-cancer drug called Taxol is extracted from the bark

1. TAXUS

2. MORPHOLOGY
• It is an evergreen tree attaining a height of 9-20 metres
with a massive trunk
• . The stem is profusely branched and remains covered
with a thin brown-coloured bark.
• Do not have dimorphic branches
• The leaves are linear, small, only 2-3 cm. long and spirally
arranged.
• eacvegetativesesses a single strong vein and recurved
margins.
• The upper surface is dark green while the lower surface
is pale or rusty red in colour.

4. • The apex is sharply pointed mainly because of
accumulation of silica.
• This sharply pointed apex may cause death of
catties eating these leaves.
• Each leaf is shortly stalked. The stalk broadens into
a flat persistent base which shows a slight twist.
• The scaly leaves present on the fertile shoot are
opposite and decussate.
• Taxus possesses a long and well- developed tap-
root. The roots are deep-feeders and highly
branched.

5. Anatomy of Stem

6. • It is irregular in outline and resembles Pinus in
structure.
• Thickly cuticularised single-layered epidermis.
parenchymatous cortex having some tannin-filled cells.
• It is followed by endodermis and sclerenchymatous
pericycle.
• The young stem shows a ring of conjoint, collateral,
open and endarch vascular bundles enclosing a distinct
pith in the centre.
• The protoxylem consists of spiral tracheids, and the
phloem contains sieve cells with sieve plates and
phloem parenchyma. Companion cells are absent.

7. secondary growth of the stem

8. • The cambium cuts secondary phloem towards
outer side and secondary xylem towards inner side
.
• The secondary wood is devoid of resin canals and
wood parenchyma.
• Its tracheids show uniseriate bordered pits only on
their radial walls.
• The tracheids also show spiral thickenings
• The wood is strong and dense. Due to the presence
of tertiary spirals the wood is elastic in nature.
• Phellogen may develop in the older stems showing
extrastelar secondary’ growth.

9. Anatomy of leaf

10. • The leaf is dorsiventral.
• It shows xerophytic characters.
• Upper and lower epidermal cells are rectangular in
shape and thickly circularized.
• The cuticle is comparatively thin on the lower surface.
• The stomata are of sunken type and restricted only to
the lower epidermis.
• The mesophyll is differentiated into palisade and
spongy-parenchyma.
• The palisade is generally two-layered.

11. • Only one vascular bundle is present in the mid-rib
region.
• Enclosed by a distinct endodermal layer or bundle
sheath the collateral vascular bundle contains phloem
towards the lower side and xylem towards the upper
side.
• Transfusion tissue is present on both the sides of the
vascular bundle.
• Resin canals are generally absent.
• The xerophytic characters of the leaf include the
presence of thick cuticle, sunken stomata, transfusion
tissue and differentiation of mesophyll into palisade
and spongy parenchyma.

12. Reproduction in Taxus
• Taxus is usually dioecious, but occasionally
monoecious trees are also reported
• vegetative reproduction is absent

13. Male strobilus or male flower
• The ‘male flowers’ or ‘male strobili’ are usually
yellowish in colour and develop in the axil of foliage
leaves .
• Each strobilus contains a number of overlapping
sterile bracts Some of the bracts towards the tip of
the strobilus are replaced by stamens or micro-
sporangiophores.
• Each stamen is shortly-stalked any has a peltate
disc bearing 4-8 pendant microsporangia

15. • Each stamen is shortly-stalked any has a peltate
disc bearing 4-8 pendant microsporangia.
• The microsporangia surround the stalk
completely
• The microsporangia in the young male strobilus
are compactly arranged but at maturity they get
loosened and undergo dehiscence.
• The presence of peltate micro-sporangiophores is
one of the most remarkable features of Taxus.

17. Female strobilus or Female cone
• The female strobili
in Taxus are so
highly reduced that
they hardly appear
as cones or strobili.
• They arise in the
axils of leaves early
in the season and
mature in the next
season.

18. • Each female reproductive organ consists of a
short primary axis having scaly leaves or bracts
arranged in opposite decussate manner
• A short secondary axis develops from the axil of
upper three scaly leaves.
• This secondary axis bears a few pairs of scaly
leaves and a terminal ovule .
• According to Dupler (1920) the primary axis
functions only as a vegetative branch of limited
growth bearing the reproductive secondary
axis.

20. Structure of Ovule
• The ovule is orthotropous
and sessile.
• A single thick
integument is present.
• Integument is free from
the nucellus right up to
its base
• formingegument is
differentiated into outer
fleshy, middle stony and
inner fleshy layers

21. • A ring-like outgrowth develops from the base
of the integument. It surrounds the entire
ovule. It is called ‘aril’ or ‘cupule’ .
• Aril is green and saucer-shaped when young
but at maturity it is red and cup-shaped.
• Pollen chamber and nucellar beak are absent in
Taxus.
• The apex of the female gametophyte changes
into a flask-shaped structure called tent-pole.
The tent-pole disappears in the later stages.

22. • Generally, up to 10 archegonia develop in the
female gametophyte but sometimes as many
as 25 archegonia may appear.

23. Seeds
• Taxus seeds are covered by a three-layered
seed coat.
• The outermost layer is thin, brown and
detaches soon.
• The middle layer is hard and stony while
the innermost layer is fleshy.
• The mature seeds are covered by a red
coloured aril. The aril serves to attract birds
and help in dissemination.

25. Economic Importance
• widely cultivated as an ornamental plant.
• The timber of Taxus baccata and some
other species is oily and heaviest of the soft
woods.
• It is quite durable and used for making
decorative veneers, turnery, flowers and
posts. Several other types of decorative
pieces are also made from its wood.

26. •Due to the presence of a toxic alkaloid
(taxine) in the leaves, shoots and
seeds, the entire plant of Taxus
baccata is considered poisonous and
also used in some countries as a fish
poison.
•Its leaves also contain traces of
ephedrine, and, therefore, used in
bronchitis, asthama and epilepsy.
Seeds of T. baccata are used as
sedative.

27. • Taxol is a drug obtained from the bark of
taxus tree.Taxol is used for the treatment
of breast, ovarian, lung, bladder, prostate,
melanoma, esophageal, as well as other
types of solid tumor cancers.

28. Thank You...