THE GEls'US MANETTIA 7 



Calyx turbinatus v. subcylindricus v. campanulatus plerumque ad 

 basin lobatus, basi nonnunquam breviter tubularis tubo plus minus ad 

 discum adnato ; lobi saepius 4 denticulis nonnunquam interjectis, nunc 

 parvi inconspicui nunc elongati angusti ssepe subsetacei nonnunquam 

 ampli foliaeei. Corolla clavata v. tubulosa majuscula v. parva hypo- 

 crateriformis nonnunquam anguste infundibularis rarius campanulata ; 

 limbi lobi ssepissime 4 breves pro rata latiusculi rarissime tubum 

 excedentes. Stamina 4 corollse in ore v. faucibus inserta filamentis 

 brevibus antheris versatilibus. Discus pulvinaris v. annularis. 

 Ovarium biloculare ; ovula in loculis numerosa in placentis septi a 

 basi erectis imbricata, Capsula turbinata v. ovoidea v. oblonga, plus 

 minus sulcata, ab apice septicide bivalvis polysperma, ealyce persistente 

 coronata. Semina placentis iii turaidis erectis peltatim imbricata, 

 nucleo complanato ala conspicua cineto irregulariter dentata. HerbcB 

 vel suffrutices volubiles eaulibus gracilibus,/b/'u's pro rata latis, stipulis 

 breviter vaginantes. Flores majusculi v. plerumque parvi albi cierulei 

 vel rubri axillares saepius singuli bini vel pauei lateralibus in ramulis 

 brevibus dispositi raro fasciculati umbellatlm dispositi folia rare 

 excedentes. 



Its dry 2-valved capsular fruit containing many winged seeds, and 

 its valvate regular corolla, entitle Manettia to a place in tbe Eucin- 

 chonea3 subtribe ; it is distinguished from all the rest except Hindsia 

 by the erect placenta, which is tixed to a point near the base of the 

 septum. The few species of Hindsia are small erect shi*ubs with 

 terminal inflorescences of slender long tubular flowers. Souvardia 

 also is an allied genus, in which the tendencies of the flowers to be 

 aggregated into dense terminal inflorescences is realized in nearly all 

 the species ; this tendency we proceed to trace in the following pages 

 among the species of Manettia. Bouvardia is a genus, of consider- 

 able size, of erect herbs and small shrubs. 



The key to the species that follows is confessedly artificial, having 

 for its object the specific determination of any given Manettia Aviththe 

 greatest possible speed, by means, therefore, of the most obvious and 

 readily perceivable characters. It follows that the first two sections, 

 § Pyrrhanthos and § Heterochlora, are clearly separated in the key ; 

 while the other two, the small-flowered sections § Lygistum and 

 § Ysginanthus, are mingled indiscriminately. The artificial nature of 

 the key appears also in the criteria of leaf-size and corolla-tube length ; 

 in regard to these items it is scarcely necessary to point out that any 

 key must be employed with caution. In the more difficult cases the 

 same species appears more than once : so that this clavis must not be 

 taken to reflect anything approaching an evolutionary grouping. In 

 the general systematic account of the species which follows they are 

 arranged and' numbered as far as possible in accordance with their 

 mutual affinities. 



Specific Affinities. 



In this connection it may be desirable to draw attention to one or 

 two evolutionary tendencies observable within the genus. 



In the NeioPTiytologist, x., xi. (1911-2)— " Floral Evolution" — 



