ROBINSON.— ALOMIA, AGERATUM, AND OXYLOBUS. 455 
and technical characters, and several are scarcely to be separated 
from Trichogonia except by their slightly shorter and thicker pappus- 
bristles. Their satisfactory generic disposition must await further 
study, for which there is no adequate material as yet available in the 
North American herbaria. 
The other two elements traditionally included in Ageratum, namely, 
the true Ageratums with pappus of distinct scales, and Coelestina Cass. 
with cuplike or crownlike pappus, are groups of very close affinity, 
by no means sharply separable. It is believed that they are best 
treated merely as sections of the genus Ageratum. 
The writer has not had many opportunities to follow up the various 
forms of Ageratum which have received horticultural names. So far 
as seen these have proved merely cultural improvements of the com- 
mon annuals, A. conyzoides L. and especially A. Houstonianum Mill. 
A. rubens Viviani, early described from cultivated material, has never 
been recognized. A. Lasseauxii Carr., to judge from a supposably 
authentic specimen in the Gray Herbarium, is clearly a species of 
Eupatorium. A. conspicuum Hort. is generally believed to have been 
Eupatoriumglechonophyllum Less. Ageratum Wendlandii of Vilmorin’s 
Fleurs de pleine terre, Suppl. 2 (1884), with uncharacteristic figure 
and mere horticultural description, was presumably founded on the 
same plant as the one to which Schultz-Bipontinus applied the manu- 
seript name Phalacraea Wendlandii, later published in synonymy by 
Klatt. If this is the case Vilmorin’s plant was the one described else- 
where in this paper as Alomia Wendlandii and came from the uplands 
of southern central Mexico. It would seem probable that both Agera- 
tum and Alomia would repay further horticultural attention, there 
being several other species quite as promising as those already brought 
into cultivation. 
AGERATUM L. (Nomen ab antiquis et graece et latinice ad 
plantam aliquem non viescentem non certe cognitam fortasse ut dici- 
tur Achilleam applicatum.)— Capitula homogama tubuliflora. In- 
volucrum plerumque campanulatum rariter turbinato-subcylindratum 
vel hemisphaericum, squamis angustis longitudine subaequalibus 2-3- 
Seriatim imbricatis (cum vel absque squamulis 1-3 extimis multo 
brevioribus) plerisque lanceolato-linearibus acutis vel attenuatis 
Saepius 2(1-4)-costatis. Receptaculum planum vel convexum vel 
conicum nudum vel paleiferum. Corolla 5-dentata limbum versus 
Saeplus caerulea vel purpurea vel alba rarius rosea, tubo proprio 
Superne sensim in fauces subcylindratas plus minusve ampliato. 
