Flower structure of maize

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M aize Floral Biology © A.K. Chhabra Floral Biology of Maize (Zea mays)

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M aize Floral Biology © A.K. Chhabra Floral Biology of Maize (Zea mays) Maize is a tall, monoecious, annual grass varying in height from 1 to 4 meters

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Maize is a monoecious plant, that is, the sexes are partitioned into separate pistillate (ear) and staminate (tassel) inflorescences. Maize Crop in the Field Tassel

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M aize Floral Biology © A.K. Chhabra It has a determinate growth habit and the shoots terminate in inflorescences bearing staminate or pistilate flowers Tassel Cob Tassel Cob

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The tassels or staminate (male) inflorescence form large spreading terminal panicles that resemble spike-like racemes. Pollen is shed from the tassel and is viable for approximately 10 to 30 minutes as it is rapidly desiccated in the air Tassel Cob Male inflorescence Female inflorescence

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M aize Floral Biology © A.K. Chhabra The reproductive phase begins when one or two auxiliary buds, present in the leaf axils, develop and form the pistillate inflorescence or female flower. The auxiliary bud starts the transformation to form a long ‘cob’ on which the flowers will be borne. COB WITHOUT SILK TO BE ADDED HERE

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From each flower a style begins to elongate towards the tip of the cob in preparation for fertilization. These styles form long threads, known as silks. The base of the silk is unique, as it elongates continuously until fertilization occurs Silk

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M aize Floral Biology © A.K. Chhabra Styles may reach a length of 30 cm, the longest known in the plant kingdom. Close-up of Silk

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M aize Floral Biology © A.K. Chhabra Maize plants shed pollen for up to 14 days Anther dehiscence In tassels

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M aize Floral Biology © A.K. Chhabra The pollen of maize, a protandrous plant, matures before the female flower is receptive Anther dehiscence In tassels Spikelets

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Silk at early stage is green in some genotypes and turns red later on. In other genotypes, it is an inherent character and remains red throughout.

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The pollen grains are very small, barely visible to the naked eye, light in weight, and easily carried by wind. The wind-borne nature of the pollen and protandry lead to cross-pollination, but there may also be about 5 per cent self-pollination. Out-crossing in maize

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Styles may reach a length of 30 cm, the longest known in the plant kingdom. Style (being unfolded) Style (being unfolded)

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M aize Floral Biology © A.K. Chhabra Styles may reach a length of 30 cm, the longest known in the plant kingdom. Style (unfolded) Cob

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M aize Floral Biology © A.K. Chhabra Stigma is receptive throughout its length and bears stigmatic hairs to receive pollen grains Magnification of style Stigmatic hairs

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Individual maize kernels, or fruit, are unique in that mature seed is not covered by floral bracts (glumes, lemmas, and paleas) as in most other grasses, but rather the entire structure is enclosed and protected by large modified leaf bracts, collectively referred to as the ear Developing kernels Silk attached to each kernel Mature kernels

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M aize Floral Biology © A.K. Chhabra The female inflorescence or ear terminates one or more lateral branches (shanks) usually borne about half-way up the main stalk. Because the internodes of the shanks are condensed, the ear remains permanently enclosed in a mantle of many husk leaves.

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The tassel is formed by a many-ranked central (uppermost) spike and several two-ranked lateral branches arranged in an usually loose panicle. Tassel

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The tassel is formed by a many-ranked central (uppermost) spike and several two-ranked lateral branches arranged in an usually loose panicle. Tassel

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M aize Floral Biology © A.K. Chhabra The tassel is formed by a many-ranked central (uppermost) spike and several two-ranked lateral branches arranged in an usually loose panicle. Tip of tassel Pair of spikelets Tassel at anthesis

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M aize Floral Biology © A.K. Chhabra The flowers are organized into paired spikelets, one member being pedicellate and other sessile. Pedicillate spikelet Sessile spikelet Arrangement of spikelets in tassel Tip of spikelet Arrangement of spikelets in tassel

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Pedicillate spikelet Sessile spikelet Pair of spikelets

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Within each male spikelet, there are usually two functional florets, although development of the lower floret may be delayed slightly in comparison to the upper floret. Each floret contains three anthers and each anther produces about 2500 pollen grains Pedicillate spikelet Sessile spikelet Two florets Three anthers Pair of pedicillate and sessile spikelets

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M aize Floral Biology © A.K. Chhabra Within each male spikelet, there are usually two functional florets, although development of the lower floret may be delayed slightly in comparison to the upper floret. Each floret contains three anthers and each anther produces about 2500 pollen grains Pedicillate spikelet Sessile spikelet Two florets Three anthers Pair of pedicillate and sessile spikelets

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M aize Floral Biology © A.K. Chhabra Within each male spikelet, there are usually two functional florets, although development of the lower floret may be delayed slightly in comparison to the upper floret. Each floret contains three anthers and each anther produces about 2500 pollen grains Pedicillate spikelet Sessile spikelet Two florets Three anthers Pair of pedicillate and sessile spikelets

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M aize Floral Biology © A.K. Chhabra Within each male spikelet, there are usually two functional florets, although development of the lower floret may be delayed slightly in comparison to the upper floret. Each floret contains three anthers and each anther produces about 2500 pollen grains Pair of pedicillate and sessile spikelets

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The kernels are tightly held on the cobs

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M aize Floral Biology © A.K. Chhabra The kernels are tightly held on the cobs PICTURE TO BE ADDED

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PICTURE TO BE ADDED OF MILLION OF POLLEN SHEDDING FROM TASSEL

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra

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M aize Floral Biology © A.K. Chhabra