o 



conditions on tlie appearance and general liabit of tlie parasite^ 

 Then certain biolofjical features require examination, such as the- 



Iiybridisation is suggfested by a study of the genus with its groups 



i)f closely related species and by some of the widely varying 



species in which the extreme ty])es are connected l)y a complete 



series of intermediate forms. Finally, the morphology of the- 



flower would repay a careful study in the field with a view to the- 



elucidation of the meaning of the attachmenl of the anthers, to 



the j)eriajith segments in the majority of the species"''" ; the iing of 



tliroat liairs in the section Ann^data where the anthers are frec;: 



the value of the apical beard and the importance and true 



character of the external glands, which in some species are so 



conspicuous a feature of the perianth. 



Be CandoUet grouped the species of South African Thesiums- 

 under the' following five sections : — 



1. 



Euthesium {Perigonium infundibulifornie vel campauu- 

 latum lobis non barbatis). 

 1. Stylus elongatus, stigma capitatum. — Species her- 



9 



baceae perennes. 

 T, juncifolknn^ 2\ Krehsil, T. angulosum. 

 Stylus abbreviatus, truncatus. — Sp. suffrutescentes. 



Yru- 



^7 



vi folium, T. hrecifoltuni, T. selofjl 

 folia HI, T. acutissimuin, T. inultlfl 



ii. /Etheothesium (Pars libera j^erigonii sub 



ticulus habitu Penaeaceae), 

 T. eiipJun !}ioides, 



iiu Hagnothesium (Flores dioici, etc., ot*.-.). 



T lies id til in. 

 iv. Discothesium (Perigonium Euthesii, Discus concavus^ 



margine liber. — Rami saepe scandentes). 

 T. galioides, T. planifolinvi, 



Frisea, Brown (Lobi perigonii intus ab ai)ice et marginibu.^ 

 barba pendente insignes). 

 1. Pili loborum pone antheras nulli.— Floi-es spicati. 



7nacrostachyum - 



fl 



2, Pili ill medio loborum. — Floras spicuti vel capitati. 

 T, gnidiaceum, T. carlnatum, T. piihescens, T. capiteU 

 latum, T. densijlorum, T. evphrasioidcs, T, mlcro- 

 ineria, T, Zeyheri, T. lohcUoidcg. 



* Ewart In his jiappr " On the starainal Iiairs of The^ium" in Ann Bot 



vi. 0692) pp. 271---2!}0 gives a careful desciiption of the structure of the tw(> 



types of perianth hair.s, but theh-pyaot function is still obscure. De Gundolle 



had previnnsly ^ivcii srme acconnt of the perianth hairs in hi^ " Note sur U 



taimlle des Santulucdcs " in Soc. Thya. et Hist. Nat. Geneve Au^^n-fc 1857 

 |)p. 11, 12. > f, - > * 



■ t "R.p^ces Welles <Jn Genre Theslum " presentees a la Societo do 

 Physuque et d Histoae Natnrelle de G -neve dans £a stance du 28 Mai, 1857. 

 par. M. Alph. de Cftndolle. 



^K 



