CHAP. I.] ACANTHACE.E. 415 



The dowers form a corymb in the Scarlet Ver- 

 bena, and a spike in some of the other kinds, 

 which elongates gradually as the flowers ex- 

 pand. The principal other genera are Clero- 

 dendron, or Volkameria, Vitex (the Chaste- 

 tree), Lantana, Aloysia (the Lemon-scented 

 Verbena), and Tectona (the Teak) which is so 

 much used in the East Indies for ship-building. 



ORDER CXLIV.— MYOPORIN^. 

 Australian and Polynesian plants, nearly 

 allied to Verbenacese. The principal genera 

 are Myoporum and Avicennia, the White 

 Mangrove of Brazil, 



ORDER CXLV.— ACANTHACE^. 

 These plants are known by the elastic open- 

 ing of the capsules, which are two-celled, and 

 the hooked points of the seeds by which they 

 are attached to the placenta. The calyx re- 

 mains on the ripe fruit, but in most of the 

 plants it is so extremely small as to be incon- 

 spicuous, and its place is supplied by three 

 large leafy bracts. The corolla varies conside- 

 rably, being sometimes two-lipped as in Justi- 

 cia, sometimes funnel-shaped as in Ruellia, 



