Objectives:
At the end of this lesson, you should be able to:
1. Identify the parts and functions flowers
2. Distinguish the forms and modifications of
flowers
3. Identify and impart the economic,
environmental, and medicinal uses of flowers
Outline of Discussion
I. Functions
II. External Structure of Flowers
III. Classification of Flowers
a. According to Class
b. According to Radial Symmetry
c. According to Parts Present
d. According to Flower Organs
e. According to Presence of Reproductive Organs
f. According to Position of Ovaries
IV. Inflorescence
V. Flowers with Medicinal Value
I. Biological Function of
Flowers
1. ________________________________
2. ________________________________
I. Biological Function of
Flowers
1.SEXUAL REPRODUCTION
- entails the fusion of reproductive cells: eggs and sperm cells.
Fusion of gametes - “fertilization” occur in the flower’s ovary.
2. ASEXUAL REPRODUCTION
- does not involve the formation of flowers, seeds and fruits.
- offspring generally form asexually when a vegetative structure (stems,
leaves, roots) of an existing plant grows, expands and then becomes
separated from the rest of the plant.
ANATOMY OF FLOWER
II. External Structure of FLOWERS
1. _________ – the tip of the floral twig ; the enlarged
portion of the flower stalk to which the other organs are
attached; where floral organs attach and originate
2. _______________ – stalk of the flower
a. ____________ –composed of the calyx (collection of
sepals) and corolla (collection of petals)
b. ____________ – small leaves at the base of a flower
stalk
*Involucre – collection of bracts
3. Sepals (Calyx) – the outermost circle of green
leaf-like structure that function for protection
and keeps an unopened flower from drying; falls
off after pollination or when flower matures
4. Petals (Corolla) – a circle of brightly colored
organs that lie inside the sepals that secrete
aromatic substances and nectar (concentrated
sugar solution)
5. Stamen –situated
inside the petals,
consist of:
a. Filament – stalk of
the anther
b. Anther – the apex of
the stamen that
contains pollen grains
(male gametophyte)
Pollen Grains – male reproductive cells; they fertilize the
ovules
6. Pistil – structure at the center of the flower
a. Carpel – ovule – bearing unit of the pistil
b. Ovary – hollow base which contains the ovules (female
gametophyte, underdeveloped seeds) that will be the fruit
c. Style – stalk of the pistil into which the pollen tube travels
during pollination
d. Stigma – flat, sticky, expanded structure at the upper end of
the style specialized to receive the pollen
Pistil – the female part of the
flower
Ovules - female reproductive cells or
eggs; undeveloped seeds
III. Classification
of Flowers
A. According to Class
1. Monocot – floral parts occur in multiples of 3
2. Dicot – floral parts occur in multiples of 2, 4
or 5, less frequently in 3s, include about 80%
of angiosperms.
Angiosperms are plants that produce flow
ers and bear their seeds in fruits
MONOCOT DICOT
B. According to Radial Symmetry
1.Regular – “Actinomorphic”- built on a wheel-like basis
where all parts of each set of organs are the same size
and shape. e.g. rose, tulip, daisy, gumamela
2. Irregular (Bilateral) – “Zygomorphic”
- can be divided along a single plan to produce two halves which are
mirror images of each other e.g. orchid, peas, beans
Corolla may be composed of
the following
◉ 1. Banner or ***standard*** – single broad
conspicuous petal
◉ 2. Wings – usually two, narrower petals
◉ 3. Keel – opposite the banner; one or two
smaller petals
C. According to PARTS PRESENT
1. Complete – has all the basic parts like the stamen, pistil, petals
and sepals
e.g. rose, lily, gumamela
2. Incomplete – lacks one or more of the floral organs
e.g. elm, wheat, grass
D. According to FLOWER ORGANS
1. Connation – floral
organs of the same
kind are fused
together
D. According to FLOWER ORGANS
2. Adnation - floral
organs are fused to
other floral organs
E. According to Presence of Reproductive
Organs
1. Perfect (Bisexual
or Hermaphroditic)
– contains both
pistil and stamen
eg// rose,
gumamela
E. According to Presence of Reproductive
Organs
2. Imperfect (Unisexual) –
lacks one of the essential
organs; contains either the
pistil or stamen only
a. Pistillate – only the pistil is
present
b. Staminate – only the
stamen is present
E. According to Presence of Reproductive
Organs
c. Monoecious – contains pistil and stamen in one plant eg// corn,
cucumber, squash
d. Dioecious – pistil and stamen are found on separate plants eg//
papaya, asparagus, willow
e. Polygamomonoecious – an individual plant with flowers plus
staminate or pistilate unisexual flowers
F. According to the Position of Ovaries
1.Hypogynous (Superior ovary)
2.Perigynous (Half-inferior ovary)
3.Epigynous (Inferior ovary)
F. According to the Position of Ovaries
1. Hypogynous (Superior ovary) – primary parts are attached to
the receptacle under the ovary
e.g. tulip, mustard, China rose, lily, magnolia
2. Perigynous (Half-inferior ovary) – the pistil is in the bottom
of a concave receptacle to the edges of which the sepals,
stamen and petals are attached
e.g. cherry, peach, plum, pea, apple, rose, strawberry
F. According to the Position of Ovaries
3. Epigynous (Inferior ovary) – the pistil is sunken into the
receptacle, with sepals, petals and stamens attached above the
ovary
e.g. honeysuckle, sunflower, cucumber, dandelion, orchids,
squash
IV.
INFLORESCENCE
IV. INFLORESCENCE
- cluster of flowers, all flowers arising from the
main stem axis or peduncle; flowers included in the
inflorescence are called florets
TYPES:
1. Single
2. Determine/Cynose
3. Compound/Synflorescence
1. Single –flowers are gathered in a single pattern
a. Raceme – florets are attached along a floral peduncle with stems similar in length;
young florets appear above and old ones below
b. Spike – similar to racemes but florets are attached directly to the floral peduncle,
without stems
c. Corymb – all the florets are arranged along a floral peduncle but stems have
different lengths such a way that all the florets appear at the same flat round level
d. Umbel – florets arise from the same point of the peduncle
e. Head or Capitulum– florets bearing no stem are gathered together on a platform-
shaped peduncle
f. Spadix – spike of flowers densely arranged around it, enclosed or accompanied by a
highly specialized bract called a spathe
g. Catkin or Ament – scaly, drooping spike or raceme
Spadix and Spathe
2. Determinate/Cymose - first-formed flower develops
from the growing region at the top of the flower stalk
- apical tissues of the main stem
and laterals lose their
meristematic capacity and
differentiate into flowers. New
growth arises from continued
cell division in the axillary
meristems. Older flowers are
usually found near the stem
apex
3. Compound/ Synflorescence - when a complex
pattern is made of another pattern
a. Panicle – formed by several racemes
gathered together
b. Compound umbel – several umbels
gathered together
c. Compound spike
d. Compound capitulum
e. Cymose corymb
f. Thyrse – a raceme in which the single
flower are replaced by cymes
V. Flowers with Medicinal Value
(***Assignment: SN, F, Use)
