The Angiosperm Plant Body • Structure and development • Formation of embryo • Mature embryo and seed • Embryo to adult
In most angiosperms, the ovule consists of three layers of tissue: • Integuments - two outer layers of diploid (2N) tissue that will develop into the seed coat. • Nucellus - the wall of megasporangium, also diploid (2N). • Embryo sac - also call the megagametophyte of angiosperms, consists of only 7 cells. Contains 8 haploid nuclei in all.
“Polarity” -Apical- basal pattern - Radial pattern
Embryo development • Orderly cell division • Differentiation leads into two distinct parts • Embryo proper • The suspensor Before this stage is reached the developing embryo is referred to as the proembryo Becomes food nourishing component
Monocot or Dicot? • Solanum caroliense
Stage of embryo development preceding cotyledon development • Globular stage- embryo proper (proembryo) is spherical • Heart stage (dicots only)- seed leaf (cotyledon) development • Torpedo stage- apical basal pattern just prior to germination
Stages of embryo development • Stages of embryo development • Globar stage • Heart stage (dicot only) • Torpedo stage
Future Epidermis Embryo proper will become - meristemic tissue Future Ground meristem (ground) and Procambium (vascular)
Forms the seed coat
(nucellar tissue) (Embryonic root)
Lets look at Seed of some common dicots and monocots • Garden bean • Castor bean • Onion • Maize
Grass embryo Mature grain or kernel of Wheat Monocot or dicot?
Grass embryo -First bud of radicle Protective layer of radicle and plumule