236 BOTANICAL EXCURS!ON 
several other species of Pycnanthemum, and in the endeavour 
to discriminate them, we encountered so many difficulties, 
that I am induced to give a revision of the whole genus.* 
* CoNsPECTUS PYCNANTHEMORUM. 
$ 1. Calyx viz bilabiatus ; dentibus bracteisque subulato-aristatis, rigidis, 
nudis, corollam equantibus. Verticillastri densi plerumque terminales. Ovaria 
barbata. Folia subpetiolata, rigida. 
1. P. aristatum, (Mz); foliis breviter petiolatis ovato-oblongis acutis 
subserratis basi rotundatis cauleque tenuissime canescenti-tomentosis vel 
glabris.—P. setosum, Nutt. in Jour. Acad. Philad. 7, p. 100, excl. syn. 
Pursh. Origanum incanum, Walt. herb. 
Has. A Nova Cæsarea ad Floridam.—Folia floralia nunc candicantia.- 
2. P. hyssopifolium, (Benth.); foliis subsessilibus lineari-oblongis ob- 
tusis subintegerrimis cauleque glabris vel tenuissime subtomentoso-ca- 
nescentibus.—P. aristatum, Pursh, (fide spec. in herb. Lamb, et herb. 
Bart.), Nutt. et Ell, 
Has. A Virginia usque ad Floridam et Louisianam.—Due species arcte 
affines optime dignoscuntur in — Lab. gen. et spec. Stamina e 
fauce corollz subexserta. 
$2. Calyx bilabiatus ; nempe sagi (plerumque subulatis, sepe pile 
rigidiusculis barbatis) 3 superioribus in labio superiore basi coalitis. Peete: 
cillastri cymosi, laxi. Ovaria sepius barbata. Folia petiolata. 
3. P. albescens, (Torr. et Gray, fl. N. Am. ined.) ; verticillastris cymosis, 
dentibus calycis zqualibus triangulari-lanceolatis obtusiusculis muticis, 
foliis oblongis ovato-lanceolatisve subserratis utrinque acutis supra glabris t 
subtus canis, 
Has. In Louisiana, Ingalls, Hale, et Alabama, Gates.—Minus per totum 
quàm P, incanum ; folis superioribus, ut in aliis utrinque candidis, 
tonat cauleque pube brevissima incanis. Ovaria ad apicem brevissime 
4. P. incanum, (Michz.) ; verticillastris cymosis, dentibus calycis sub- 
equalibus lanceolato-subulatis, apice plerumque 1-2 setosis, foliis ovato- 
oblongis remote serratis basi rotundatis pubescentibus subtus — 
mentosis, floralibus utrinque candidis, 
Folia ampla. Ovaria ut yidi villoso-barbata, non “apice attenuata, : 
appendice paleaceo a — Mihi ignotum est P. Loomisii, Nutt. in 
Jour. Acad. Philad. 7, p. 100, quod in characteribus datis omnino p.i in- 
cano convenit, 
5. P, Tullia, (Benth) ; verticillastris cymosis, (floribus omnino siiis ; 
catis in ramos subsimplices arcte secundis), dentibus calycis bilabiati 
subaequalibus e basi lanceolata longe subulato-aristatis bracteisque apicem 
