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Vascular Plants - a quick review - page 9 / 12

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Phylum Polypodiophyta

ferns

Circinate vernation: vernation is the arrangement of folded leaves in a bud, forming a crozier or fiddlehead, i.e. coiled or rolled up at the tip and unfolding lengthwise when emerging - due to auxin and differential growth of tissue. Protects young bud.

Phylum Polypodiophyta

ferns

The sprorangium is often associated with an annulus a cluster or row of cells with thick walls that open the sporangium and catapult the spores into the air.

Ferns can be either homosporous or heterosporous.

annulus

Phylum Polypodiophyta

ferns

Sporangia borne on the margin or the lower surface of the leaf; often grouped in sori (pl.) sorus (sing.); a sorus may be protected by a flap-like structure called the indusium - an important feature for identification of ferns due to its remarkable variation in size, shape, and position.

Phylum Polypodiophyta

ferns

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