Embryogeny

Proembryo

Two celled stage from initial division of the zygote. Apical (smaller) cell and basal (longer) cell

Initial embryo-proper and suspensor

apical cell divides in 2, basal cell divides into 4-6

quadrant stage

embryo has undergone a second longitudinal division resulting in 4 cells

octant stage

embryo undergoes a transverse division resulting in 8 cells. Upper tier will give rise to the epicotyl and cotyledons, lower tier to hypocotyl and radicle.

globular embryo

Periclinal division in 8 embryo cells; 16 cells including protoderm initials. Hypophysis is formed from the suspensor.

hypophysis

closest suspensor cell to embryo proper in early embryogenisis

late globular embryo—before hypophysis division

conspicuous protoderm layer

late globular embryo—primary meristem layers

hypophysis has transversely divided into a lower larger cell and a smaller upper cell. Three layers corresponding to protoderm, ground meristem, and procambium. 2 procambium cells.

origin of cotyledons

primordia of two budding cotyledons. 4 derivatives of cell division in hypophysis; will give rise to radicle and root cap

“torpedo” stage

cotyledons elongate, hypophysis derivatives numerous with the top 2-4 destined to become the quiescent center of the radicle. Endosperm cellularized

“walking-stick” stage

apical meristem of epicotyl becoming organized. Root cap and radicle well developed. Suspensor still intact and some endosperm remains. Cotlyledons bending

Mature embryo

endosperm consumed. hypocotyl, epicotyl, and radicle formed. remnants of a suspensor

phaseolus

pisum

solanum

lactuca

plumule

leaf primordia already produced by the shoot apical meristem between two cotyledons

Gingko

Number of leaf primordia in ginkgo

2

surrounding tissue of ginkgo embryo

megagametophyte tissue

pinus

number of pinus cotyledons

average 8

seed coat derivative in pinus

integument

Allium

Lilium

Triticum

no epiblast

Zea

scutellum

cotyledon of grasses

coleoptile

sheath over shoot apex in grasses

coleorhiza

sheath which covers the root apex in grasses

hypocotyl-root axis

area of the hypocotyl and root in grasses

epiblast

underdeveloped second cotyledon in triticum