modio unincrvise. Semina uniserialia, ferruginea, oblonga, ad apicem attenuata. Cotyledones graciles, in-
cumbentes.
H ab. York Factory in Hudson’s Bay, to the shores of the Arctic sea, westward of the Mackenzie River.
Dr. Richardson; Drummond; Capt. Sir John Franklin; and Capt. Back. Kotzebue's Sound and Bay of
Eschscholtz in Behring’s Straits. Chamisso; Lay and Collie in Capt. Beechey's Collection.—Numerous
specimens from very different parts of the interior and extreme north and north-west coast of America, all
agreeing in the same characters, have induced me to coincide with my friends Dr. Fischer and Dr. Richardson
in considering this species distinct from our European S. Sophia, which has generally more divided
leaves, more elongated corymbs or racemes, and shorter pods. I have not seen the true S. Sophia from any
part of North America. The species so called by Pursh, Nuttall considers to be a new plant, allied to S.
album of Siberia; while Elliott refers it to S. canescens. Our plant has much longer pods than any of the
present division with bipinnatifid leaves, except S. persicum. Dr. Fischer’s specimens of S. sophioides from
Kotzebue’s Sound, are precisely the same as ours.
Tab. XX. Plant:—natural size. Fig. 1, Flower; fig. 2, Stamen; fig. 3, Petal; fig. 4, Pod; fig. 5, Seed;
fig. 6, Embryo; fig. 7, Section of do.:—magnified.
5. S. canescens; cano-pubescens, foliis bipinnatifidis, lobis ovatis lanceolatisve obtusis
dentatis, petaUs calycem sequantibus, siliquis linearibus (brevibus) longe racemosis.
*. major; foliorum lobis angustioribus.—S. canescens. Nutt. Gen. Am. v. 2. p. 68.?
Rich, in Frankl. 1st Joum. ed. 2. App. p. 27. Elliott, Carol, v. 2. p . 147. Torrey in PI.
o f R. M. in Ann. o f Eye. N. Y. p. 166.—Cardamine? Menziesii. De Cand. Prodr. v. 1.
p . 153?
fi. minor; foliorum lobis latioribus.
H ab. a. In the low grounds, from lat. 50° to 60°. Dr. Richardson. Plentiful about the Saskatchawan
and Red Rivers. Douglas.—,fi. In the Rocky Mountains and about Fort Franklin, lat. 66°. Drummond; Dr.
Richardson. California. Mr. Menzies.—I have referred to Nuttall, the original authority, indeed, for this
species, with a mark of doubt ; because on looking over Dr. Richardson’s specimens, he was of opinion that
they were distinct from his canescens. Nevertheless, his short character sufficiently accords with our plant,
save that he describes the pods as clavate, which ours are, only in a slight degree, when the lower seeds in
the cells are abortive, occasioning a corresponding contraction in that part of the seed-vessel. I am disposed
to think the species has a very extensive range. If Nuttall’s and Elliott’s plants be the same, it is very common
in Carolina and Georgia; and I possess specimens, which I can by no means distinguish from it, gathered
near Rio Quinto, in the province of St. Louis, S. America, by Dr. Gillies.
6. S. brachycarpum; subglabrum, 'foliis bipinnatifidis, lobis lanceolatis obtusis integris
vel parciter dentatis, petalis calyce majoribus, siliquis linearibus (brevibus).— in
Frankl. ls£ Joum. ed. 2. App. p. 27.
H ab. From Canada to the Arctic Sea, and across the whole width of the Continent. Dr. Richardson.
Drummond. Great Falls of the. Columbia, in low moist soils. Douglas.—Habit of S. Sophia, but, as Dr.
Richardson well observes, easily distinguished by its pods being twice as short, scarcely different from the
preceding in that respect, from which again it is separated by its almost glabrous stems and leaves, and in
having the petals, in general, but, I think, not always, longer than the calyx. I possess some specimens
that I can with difficulty say to which they should he referred.
* * * * Arabidopsis. Siliquce lineares, compresses, stigmate sessili truncato. Flores albi (vel
subrosei) brevissime pedicellati. Pedicelli ebracteati. DC.
7. S. humile; incano-pubescens, perenne, caulibus diffusis, foliis integris vel sinuato-
dentatis radicalibus spathulatis, caulinis lanceolatis basi attenuatis, siliquis linearibus
pedicello quintuplo longioribus tereti-torulosis pubescentibus.— S. humile. Ledebour,
MSS. ined.
ec. Ledeb.; foliis subintegris.
/3. Ledeb.; foliis sinuato-dentatis subpinnatifidis.
Radix sublonge descendens, anguste fusiformis, perennis. Caules rarius solitarii, saepissime plurimi ex
eadem radice, palmares, diffusi, nunc prostrati, siraplices vel superne ramosi, pubescenti-hirsuti, non raro pur-
pureo tincti. Folia omnia magis minusve pubescenti-incana, pube ramosa, versus basin pilis immixta; in
«. subintegra, in /?. sinuato-dentata, etiam dentato-pinnatifida; radicalia oblongo-spathulata, obtusa; caulina
lanceolata, etiam obtusa, rarius subacuta, basi in petiolum attenuata. Flores in corymbis parvis terminalibus,
majusculi, albi vel pallide purpureo-rosei. Pedicelli calycem subsequantes. Calyx puhescenti-hirtus, pilis
ad apicem longioribus; sepalis late ovatis, concavis, erectis. Petala calyce plusquam duplo longiora,
unguiculata, limbo lato, patente, subretuso. Pistillum: germen cylindraceum, valde pubescens: Stigma sub-
sessile, obtusum, vix capitatum. Siliquce in racemis triuncialibus, pollicem longa?, subcurvafee, lineares, teretes,
torulosse, puhescentes, in acumen breve terminantes. Semina uniserialia, ovalia, fusca. Cotyledones
incumbentes.
Hab. a. Rocky Mountains, between lat. 52° and 57°. Drummond.—p. About the Mackenzie River,
from lat. 60° to 68°. Dr. Richardson. Drummond.—This plant has so entirely the habit of some states of
Arabis petraa, that, were it not for the more rounded and torulose pods, I should probably not have ventured
to separate them. An examination of the seeds, however, soon convinced me that the plant must be far
removed from the genus Arabis, as it now stands; and on comparing it with my specimens of Sisymbrium
humile, communicated by Professor Ledebour, from the Altai, I find them in every respect to correspond;
and the two varieties of our North American Travellers precisely agree with the a. and /?. of that excellent
Botanist. -
8. S. arabidoides; annuum, foliis radicalibus lyrato-pinnatifidis subhirsutis, caulinis linearibus
integerrimis cauleque erecto ramoso glaberrimis, siliquis erectis linearibus strictis
pedicello duplo longioribus. (Tab. XXI.S-Arabis lyrata. Linn. Sp. PI. p. 929. Pursh,
FI. Am. v. 2. p. 437. De Cand. Prodr. v. 1. p . 146. Rich, in Frankl. ls£ Joum. ed. 2. App.
p. 26.—(These syns. to be expunged from A. petrosa, p. 42 of this work.)
Radix parva, annua, subfusiformis. Caules erecti, spithamsei et ultra, solitarii, vel plurimi ex eadem radice,
glabri, subglauci, flexuosi, ramosi. Folia radicalia unciam duas tres uncias longa, in rosulam expansa, lyrato-
pinnatifida, lobis brevibus inferioribus acutis, parce pilosa. Caulina linearia, subunciam longa, integerrima,
omnia magis minusve infeme in petiolum attenuata. Pedicelli floris longitudine, glaberrimi. Calyx
omnino glaber, foliolis ovatis. Petala oblongo-obovata, calyce plusquam duplo longiora, alba vel purpuras-
centia. Siliqua sesquiunciam fere ad duas uncias longa, pedicello duplo longior, erecta, stricta, anguste
linearis, stylo brevi terminata. Stigma parvum, capitatum. Semina uniserialia, ovalia, rufo-fusca. Cotyledones
incumbentes.
H ab. Common on the banks of rivers, from Canada to lat. 68°, and in dry or waste places. Dr. Richardson.
Numerous specimens of this plant are in Dr. Richardson’s collection, with flowers and fruit. At first I had
referred it to what I then considered a variety of A. petrcea, the A. lyrata of Linn. In this opinion
I feel almost sure I am correct, and hence I have adopted that synonym above. But the cotyledons
are decidedly incumbent, and the root is annual. Besides these important characters, by which our plant
may be known from A. petrcea, I find its pods to be more upright, longer, and straighter, especially when
perfect. In other respects, particularly in the form of its leaves, and the size and appearance of its flowers,
the two are almost identical. Linnaeus well observes of his Arabis lyrata, “ Statura et habitus A. thaliance,
praeter quod folia radicalia lyrata, glabra et flores majores.” And Arabis thaliana is equally a Sisymbrium
having incumbent cotyledons.—Whether or not the Arabis ambigua of De Candolle, and Chamisso, and