Agents of Pollination

Wind and water pollinated flowers do not need visual cues or rewards like nectar because their vectors are abiotic, making Assertion true. They produce copious pollen to compensate for random passive dispersal loss, making Reason true. However, R is not the explanation for A.

Wind pollination is a chance event, so wind-pollinated flowers produce enormous amounts of light, non-sticky pollen and have well-exposed stamens and large, feathery stigmas.
Such flowers often have a single ovule in each ovary and numerous flowers packed into an inflorescence, e.g., the corn cob, where each grain develops from an ovary with one ovule.
Having one ovule per ovary suits the low probability of many pollen grains landing on the same stigma.
Flowers pollinated by bees, butterflies and birds usually receive many pollen grains in a single visit and commonly have ovaries with many ovules.
Hence plants with ovaries having one or a few ovules are generally pollinated by wind.

Wind-pollinated flowers produce light, non-sticky pollen in large amounts, have well-exposed stamens and large, often feathery stigmas to trap air-borne pollen, and often have a single ovule in each ovary.
NCERT states that wind pollination is quite common in grasses; the tassels of the corn cob are the stigmas and styles that wave in the wind to trap pollen.
Orchids, legumes and lilies have showy, coloured flowers with nectar or other rewards and are pollinated by insects.
Hence wind pollination is common in grasses.

Wind pollination is a chance event, so the flowers produce enormous amounts of pollen to compensate for the loss.
The pollen grains are light, dry and non-sticky, so that they can be carried by wind currents.
The flowers are small and inconspicuous, without bright colours, fragrance or nectar, since they do not need to attract animals; they have well-exposed stamens and large, feathery stigmas.
Bright colours and nectar are features of insect- or bird-pollinated flowers.
Hence wind-pollinated flowers are small and produce a large number of dry pollen grains.