Similarities of Gymnosperms with Pteridophytes and Angiosperms

Similarities of Gymnosperms with Pteridophytes:-

i. Sporophytic, independent plant body is present in both the groups. It is differentiated into root, stem

and leaves.

ii. Sporophyte possess a well-developed vascular tissue.

iii. Xylem lacks vessels and phloem companion cells.

iv. Young leaves show circinate vernation.

v. Presence of megaphyllous leaves.

vi. Gymnosperm and few pteridophytes e.g. Selaginella are heterosporous i.e. form micro- and

megaspores in micro- and megosperangia, borne on the micro and megasporophylls respectively.

vii. In Cycas, sporangia are grouped in sori like pteridophytes.

viii. The female sex organ is archegonium in both the groups.

ix. The male gametes of Cycas and Ginkgo are motile like the pteridophytes.

x. Permanent retention of megaspore within the megasporangium.

xi. Gametophytes are endosporic and highly reduced.

xii. Female prothallus develops before fertilization and there is free nuclear division.

xiii. Germination of spores is precocious in gymnosperms and hetrosporous pteridophytes.

xiv. Development of distinct embryo after fertilization.

xv. Like the pteridophytes, gymnosperms show marked alternation of generation between

gametophytic and sporophytic phase. Sporophytic generation or sporphytic phase is dominant,

independent and large at maturity while the gemetophtic generation exhibits progressive reduction and

dependence.

Similarities of Gymnosperms with Angiosperms:-

i. Main plant body is sporophytic and is differentiated into root, stem and leaves.

ii. Plants are trees or shrubs and may be erect or climbing.

iii. Root system is well developed and the roots may be diarch, triarch, tetrach or polyarch.

iv. The xylem is exarch in the roots.

v. Stem is eusteltic. Vascular bundles are conjoint, collateral, open and endarch.

vi. Secondary growth takes place.

vii. Wood may be monoxylic or polyxylic.

viii. Vessels and companion cells also occur in some gymnosperms (Gnetales) like angiosperms.

ix. Heterosporous and have reduced gametophytes.

x. Nucellus is surrounded by integument to form a structure called ovule.

xi. Like gymnosperms many angiosperms are wind pollinated.

xii. Megaspore permanently remains inside the megasporangium and develops into female

gametophyte.

xiii. Pollen grains grow into pollen tube.

xiv. Male gametes are non-motile in majority of gymnosperms and angiosperms.

xv. Fertilization is siphonogamous.

xvi. Suspensor is formed during development of embryo.

xvii. Formation of endosperm.

zviii. Formation of seeds from ovules.

xix. As in gymnosperms, polyembryony is found in several angiosperms.

xx. Embryogeny is endoscopic.

xxi. Life cycle is similar in both groups.