Phyllotaxy                                                  swollen end of the stalk or pedicel called
                                                            thalamus or receptacle.
It is the pattern of arrangement of leaves on              The four whorls are Calyx, corolla,
the stem of branch.                                         Androecium and Gynoecium.
                                                           Calyx and corolla are accessory organs.
Alternate : a single leaf arises from each node
                                                           Androecium and Gynoecium are
Opposite : a pair of leaves arise at each node              reproductive organs.
and lie opposite to each other.                            In flower like lily, the calyx and corolla
                                                            are indistinct and are called perianth.
Whorled : more than two leaves arise at a                  Bisexual: flower having both Androecium
node and form a whorl.                                      and Gynoecium.
                                                           Unisexual: flower having either stamens
Modifications of leaves                                     or carpel.
Leaves are often modified to perform functions
                                                        Pattern of flower
other than photosynthesis.
                                                           A flower may be trimerous, tetramerous or
    Modified to tendril for climbing as in peas.           pentamerous when the floral appendages
    Modified to spines for defense as in cacti.            are in multiple of 3, 4 or 5 respectively.
    Fleshy leaves of onion store food.                    Reduced leaf found at the base of the
    In Australian acacia, the leaves are small             pedicel are called bract.
     the short-lived. The petioles expanded,               Flowers which bears bract are said to be
     become green and synthesize food.                      bracteates.
    In insectivorous plant leaves are modified            Flowers without bract are said to be
     to trap insects e.g. pitcher plant, Venus fly          ebracteate.
     trap.
                                                        Parts of a flower
Inflorescence
It is the arrangement of flowers on the floral
axis of stem.
A flower is a modified shoot
    Apical meristem changes to floral
     meristem.
    Internodes do not elongate and the axis
     gets condensed.
    The apex produces different kinds of floral
     appendages laterally at successive nodes
     instead of leaves.
Racemose is the main axis continues to grow;
the flowers are borne laterally in an acropetal
succession.
Cymose is the main axis terminates in flower,           Calyx
hence limited to grow. The flowers are borne
in a basipetal order.                                      It is the outermost whorl
                                                           Each member called sepals.
                                                           Sepals are green leaf like protect the
                                                            flower in the bud stage.
FLOWER                                                     Gamosepalous: sepals are united.
                                                           Polysepalous: sepals are free.
    Atypical flower has four different kinds of
     whorls arranged successively on the
                                                   456