On Hydrothrix, a new genus of Pontederiaceae. 
BY 
Sir J. D. HOOKER, K.C.S.I., F.R.S. 
With Plate VII. 
F LORES minuti, axillares, per paria spatha propria et 
bracteis % primum inclusi. Perianthium hyalinum, 
6-lobum, lobis linearibus inaequilongis, postico latiore. 
Stamen i, tubo perianthii insertum, lobo dorsali oppositum, 
filamento subulato ; anthera basifixa, breviter oblonga, rimis 
lateralibus dehiscens ; pollen minutissimum. Ovarium fusi- 
forme, in stylum alabastro deflexum angustatum, i-loculare, 
stigmate minuto subflabellatim 3-3-lobo ; ovula plurima, 
placentis 3 parietalibus funiculis brevibus affixa, adscendentia, 
anatropa, micropyle infera. Capsula fusiformis, follicularis, 
stylo persistente terminata, polysperma, rima ventrali dehis- 
cens, demum in valvas 3 lineares seminiferas loculicide fissa. 
Semina oblonga, teretiuscula ; testa coriacea, pallide brunnea, 
tenuissime striata et transversim striolata ; albumen sat 
copiosum, dense farinosum ; embryo rectus, longitudine fere 
albuminis, bacillaris, versus extremitatem radicularem paullo 
dilatatus truncatus, plumula minutissima, cavitate laterali 
radiculae propius immersa. — Herba Brasiliensis aquatica , irn- 
mersa , caespitosa , dichotome ramosa , glaberrima , dense foliosa ; 
caulibus gracilibus , radicibus densissime fibrosis. Folia fasti - 
giatim verticillata , verticillis polyphyllis , basi vagina communi 
circmndatis , filiformia , jlaccida , integerrima , nervis parallelis 
valde obscuris et canalibus resiniferis percursa ; vagina infun - 
dibtdif ormi-campanulata^ hyalina , basi folio elongato recurvo 
stipata , enervis. Flores apice pedunculi brevis v. elongati 
[Annals of Botany, Vol. I, No. II. November 1887. ] 
H 
