THALAMIFLOR^. 



473 



Sepals 4 5 {fig- 891), either distinct or coherent at base, im- 

 bricated. Petals 4—5 {fig. 891), rarely 0, hypogynous, alternate 



Fig. 891. 



Fig. 892. 



Fig. 893. 



JTifir. 891. Diagram of the flower of the YLorse-che&irmt {^scnJnn Hiitjio- 

 castanum). Fig. 892. Vertical section of tlie flower of the Horse- 

 chestnut. Fig. 893. Vertical section of the seed of tlie Horse-chestmit. 



with the sepals, imbricated, naked or furnished with an appen- 

 dage on the inside. Stamens 8 — 10, rarely 5 — 6 — 7 {fig. 891), 

 or very rarely 20, inserted into the disk or into the thalamus; 

 filaments distinct or slightly nionadelphous ; anthers introrse, 

 bursting longitudinally. Disk fleshy or glandular. Ovary 

 usually 3-eelled {fig. 891), rarely 2 or 4-celled, each cell con- 

 taining 1, 2 {fig. 717), 3, or rarely more ovules ; style undivided, 

 or 2 — 3-cleft. Fruit either fleshy and indehiscent ; or capsular, 

 or samaroid, with 2—3 valves. Seeds {fig. 893) usually arillate, 

 exalbuminous ; embryo rarely straight, usually curved {fig. 893), 

 or twisted in a spiral direction; co2!yfec?ows sometimes very large ; 

 radicle next the hilum. 



Diagnosis. — Flowers unsymmetrical, hypogynous. Sepals and 

 petals 4 — 5, imbricated, the latter commonly with an appendage. 

 Stamens never agreeing in number with the sepals and petals, 

 and inserted on a fleshy or glandular disk, or upon the thalamus ; 

 anthers bursting longitudinally. Fruit usually consisting of 3 

 carpels. Seeds commonly 2, sometimes 1 or 3, or very rarely 

 more, exalbuminous, usually arillate and without wings ; embryo 

 almost always curved or spirally twisted. 



Division of the Order, and Examples of the Genera.— This 

 order is divided into 4 sub-orders, as follows : — 

 Sub-order 1. Sapindem. Leaves alternate. Ovules usually 



solitary. Embryo generally curved, or sometimes straight. 



Examples :- — Sapindus, Nephelium. 

 Sub-order 2. Hipp)ocastanea. — Leaves opposite. Ovules 2 in a 



cell, of which one is ascending, and the others suspended 



