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340
NOTES OF A BOTANIST
few other perennial grasses, chiefly species of Panicum and
Paspalum, besides the Grama dulce (Cynodon dactyloii), originally
brought from Europe, but here so completely naturalised that, if
allowed to spread, it would exclude almost every other plant. It
is valuable as an article of fodder. A few annual grasses, chiefly
species of Eragrostis, grow about the outer margin of the vega.
Of sedges also (species of Cyperus and Scirpus) there are four
or five species.
Other herbaceous or suffruticose plants are a tall Polygonum,
the handsome Typha Truxillensis, the Yerba blanca ( Teleianthera
peruviana\ several species of Chenopodium, including the strongsmelling
Paico ( Ch. ambrosioides and multifidum) ; a Cleome, a
Portulaca, Scoparia dulcis, a Stemodium, and three or four other
Scrophulariaceae ; a Melilotus, a Crotalaria, a pretty Indigofera,
with numerous prostrate stems spreading every way from the
root, and pink flowers, a Desmodium, a sensitive - leaved
Desman thus, a Sonchus, Ambrosia peruviana, and a few other
Compositse; a Datura, two species of Physalis, Dictyocalyx Miersit,
Hook. f. (exceedingly variable in the size and shape of its leaves),
and the ubiquitous Solatium nigrum ; Verbena littoralis, two
species of Lippia, Tiaridium indicum, a Heliophytum, three
Euphorbias, a small Lythracea allied to Cuphea, and a few-
others.
In the river itself occasionally grows a Naias, in dense
masses, like those of Anacharis ahinastruin in English streams
and ponds. . . .
Two mosses, both species of Bryum, are occasionally found
on the banks of the river Chira, and on the filtering-stones kept
in houses, but only in a barren state.
I did not remain long enough in the country to witness the
full effect of the rains of 1864 on the desert. The first plant to
spring up, in the ravines leading down from the tablazo to the
valley, and then on the tablazo itself, were two delicate Euphorbia?,
distinct from those of the vega. A little later on they were followed
by a fragile dichotomously branched Scrophulariacea (which
is common on the coast to northward of Guayaquil) ; two viscid
Nyctagineae (species of Oxybaphus) with pretty purple flowers ;
and
two or three grasses (one of them an Aristida), but very sparingly.
The Yuca de caballo (Martyniae sp.) also began to put forth its
leaves, but the Yuca del monte had not, up to the 2oth of April,
shown itself above ground. I had seen far more wonderful
effects of the rains of 1862 at Chanduy, where a desert nearly
as bare as that of Piura became clad in a month's time with a
beautiful carpet of grasses, of many different species, over which
were scattered abundance of gay flowering plants. Something
similar must have occurred this year to northward of the hills of
Mancora, for people who travelled between Amotape and Tumbez