BIOLOGY – Plants with Seeds – Gymnosperms and Angiosperms

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BIOLOGY

Plants with Seeds – Gymnosperms and Angiosperms

* Plants with well differentiated reproductive tissues that ultimately make seeds are called phanerogams.

Gymnosperms

* This term Gymnosperms is made from two greek words: gymno– means naked and sperma– means seed.

* The plants of this group bear naked seeds [ovules are not enclosed by any ovary wall] and are usually perennial, evergreen and woody.

* One of the gymnosperms, the giant redwood tree Seguoia is one of the tallest tree species.

* The roots are generally tap roots

*The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind.

* The gymnosperms are heterosporous; they produce haploid microspores and megaspores.

* Unlike bryophytes and pteridophytes {Bryophytes – Pteridophytes }, in gymnosperms the male and the female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes.

Angiosperms

* This word is made from two greek words: angio– means covered and sperma– means seed.

* Unlike the gymnosperms where the ovules are naked, in the angiosperms or flowering plants, the pollen grains and ovules are developed in specialised structures called flowers.

* The male sex organ in a flower is the stamen.The female sex organ in a flower is the pistil or the carpel.

Monocots and Dicots

* On the basis of the number of cotyledons present in the seed, the angiosperms are divided into two groups

* Plants with seeds having a single cotyledon are called monocotyledonous or monocots. Plants with seeds having two cotyledons are called dicots.

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