Q.Differentiate between
a. Bract and Bracteole
b. Pulvinus and petiole
c. Pedicel and peduncle
d. Spike and spadix
e. Stamen and staminoid
f. Pollen and pollenium

Each pair below names two related but distinct floral or leaf structures.

a. A bract is a reduced, leaf-like structure found at the base of a flower's stalk, giving a bracteate flower; a bracteole is a smaller, secondary bract found further along, closer to the individual flower itself.

b. The pulvinus is a swollen, cushion-like part of the leaf base seen in some leguminous plants, while the petiole is simply the leaf's stalk that attaches the blade to the stem.

c. The pedicel is the stalk of a single, individual flower on which the thalamus sits, while the peduncle is the stalk or main axis of the whole inflorescence bearing several flowers.

d. A spike and a spadix are both types of inflorescence with an elongated axis bearing stalkless flowers, a spadix differing in usually being enclosed by a large, showy bract.

e. A stamen is a normal, pollen-producing male reproductive unit of the androecium, while a staminode is a sterile stamen that does not produce pollen. …

Going through each pair in turn:

• Bract and bracteole: A bract is explicitly described as a reduced leaf found at the base of the pedicel, whose presence makes a flower bracteate. A bracteole is a related but smaller, secondary bract, typically found closer to the individual flower rather than at the very base of the main flower stalk; this chapter's own notes describe the bract but not the bracteole specifically.
• Pulvinus and petiole: The petiole is the stalk of the leaf, helping hold the blade to the light and allowing it to flutter and cool in the wind. In some leguminous plants, the leaf base itself becomes swollen into a distinct cushion-like structure called the pulvinus, so the pulvinus is a specialised part of the leaf base rather than the stalk itself.
• Pedicel and peduncle: The pedicel is identified as the stalk on which the thalamus, and hence the individual flower, is borne. A peduncle, by contrast, is the stalk or main axis of the whole inflorescence carrying several such flowers; this chapter's own notes mention the pedicel but do not separately define the peduncle.
• Spike and spadix: Both are types of inflorescence with an elongated axis bearing many stalkless flowers, a spadix typically being distinguished by a large, often colourful enclosing bract called a spathe; neither term is discussed in this chapter's own notes.
• Stamen and staminode: The androecium is composed of stamens, the normal pollen-producing units, but a sterile stamen that does not produce pollen is specifically called a staminode. …

Method: Group the Six Pairs by the Type of Distinction

Six pairs at once are hard to hold in memory as six separate facts. Instead, notice that the pairs naturally fall into three types of distinction, and handle each type with its own one-line rule.

Type 1, position along the plant, bract and bracteole, pedicel and peduncle: the smaller, position-specific, closer-to-the-flower structure is the individual one, the larger-scale structure covers the whole inflorescence. Bract, base of one flower's stalk, versus bracteole, a smaller, secondary bract even closer to the individual flower. Pedicel, stalk of one flower, versus peduncle, stalk or axis of the whole inflorescence, carrying several flowers.

Type 2, a structural swelling or extra feature, pulvinus and petiole, spike and spadix: one member of the pair is the plain structure, the other is that same structure plus one added feature. Petiole, plain leaf stalk, versus pulvinus, the same leaf-base region, but swollen into a cushion, seen in some legumes. Spike, plain elongated axis of stalkless flowers, versus spadix, the same kind of axis, plus a large enclosing bract called a spathe. …