ORDER EPHEDRALES / GNETALES
Ephedrales includes family ephedraceae . Family ephedraceae is monotypic and represented by Ephedra only .
Ephedra
Ephedra foliata is only species found in India ( Punjab and Rajasthan ) . Ephedra is source of drug ephedrine . Aromatic beverage mormon tea is also brewed from the species of ephedra . Most species of ephedra are shrubs . They have tap root , Stem is profusely branched , jointed and differentiated into nodes and internodes . The number of branches is equal to the number of leaves present at the node . Due to the jointed nature of stem and whorled branches Ephedra is commonly known as jointed fir . It resembles equisetum . Leaves are minutes , scaly and sessile . Only stem shows secondary growth in ephedra . In the presence of vessels in the xylem ephedra resembles angiosperms but vessels have different origins . Ephedra vessels show size variation according to season . There is a plate like structure of lignified cells in the node called nodal diaphragm . Stem of ephedra easily breaks at node due to the presence of nodal diaphragm .
Ephedra are strictly dioecious . Cones ( male or female ) arise in whorls in the axil of leaves . Each male cone has many paired bracts ( perianths ) . Stamens ( male flower ) arise from between bracts of pairs . Each stamen has a stalk ( microsporangiophore ) and anther ( 2-8 microsporangia ) .Thus male cone of ephedra is comparable to inflorescence . Male gametophyte of ephedra shed at 5 celled stage .
Female cone is usually smaller than male cone . Each cone has 2-4 bract pairs . Most bract pairs are sterile , only two upper bracts have an ovule ( one for each ) . Ovules are orthotrpous and unitegmic .
Ephedra shows double fertilization like phenomenon ( fusion with egg and venter canal nucleus ) .Pollination is anemophilous . Fertilization in ephedra is siphonogamous . Ephedra shows embro sac polyembryony . Seed germinationn is epigeal .