11 



Section I. — Imeerbia. 

 Sii!)seclion i. — Subglabra. 



V ■ f 



PeriaiLth-^cgmeiits glalmuis or fringed wiili miiiule pnpillac, 



anthers attached to se^nnonts by a tuft of hairs: — 

 1. I'lowers usually single in the bract axils 



and arranged in simple terminal 

 spikes or racemes: — 

 Planls with rigid spine-like branches, 



leaves spinous, spinulose, scale- 

 like or, if leafv, fuj^aeious : — 

 LeaA^es spinous or spinulose : — 

 Leaves stout, all spinous: — - 



Leaves folded, decurrent ... T. spinosum. 

 Leaves solid, terete, not de- 

 current ... T. pnvgens. 



Upper leaves sjnnulose, lower 



lineal 



Leaves not spinous : — 



Branchlets spinous, stems sulcate, 



T, spinulosum. 



leaA^es linear, fugacious ... T. llncalnm. 



T. rJguhan, 



JJranchlets spinous, leaves scale- 



llKG ••• ••• ■•' ••• 



Tlants not spinous, herbs or sub- 

 shrubs, leaves herbaceous or 



fleshy: — 

 Flowers with Avell-marked perianth-tube : 



Plants hairy TJiu'suUnn. 



Plants glabrous: — 



Plants Avith Aveak straggling 



]>ranches T. rircns. 



Plants Avith erect stiff branches : — 

 Plowers pedunculate, bracts 



slightly adnate to ped- 

 uncle, leaA'es liard, acutely 



acuminate T. costntu m . 



rioAxers sessile, or if shortly 



pedunculate bracts Avholly 



adnate, leaA'es herbaceous : — 



Stems tall, leaves l'2-3 cm. 



lono* ... T. Nafionae. 



Stems short, leaves So, 



1 cm. lone: T.raccmosum. 



Plowers without maiked perianth- 

 tube and mo]*e or less pro\'ided 

 Avith a disc : — 



Leaves succulent 

 1 



* « 



f 



Plants minutely scabiid ... T. disci f. 



Plants glabrous: 



Plowers pedicellate in axils of 



leafy bracts, bracteoles 

 A-ery small, inflorescence 

 indefinite, bracts not ad- 

 nate to pediocls T.vamnquem^e. 



