be ranked as species. The serratures and tufts of hair on the underside of the leaves are undoubtedly variable,
and we know how little dependence is to be placed upon the foliage of our own Cerasus Padus, a species
so nearly allied to this, that M. Scringe (in De Candolle) seems to doubt if it be really distinct.
TRIB. II. SPIRiEACEJE. DC.
3. PURSHIA. De Cand.
Cal. tubulosus 5-fidus, lobis ovatis obtusis. Pet. 5 obovata unguiculata cum staminibus
25 calycis ore inserta. Ovarium 1 (“ 2 ex Br.”) oblongum liberum stipitatum pubescenti-
glandulosum stylo subulato attenuatmn. Stigma lineare laterale longitudine fere styli,
pubescens. Ovulum unicum paulo supra basin insertum in parietem loculi adscendens. Ach-
enium (rima longitudinali dehiscens, DC.) oblongum utrinque attenuatum, stylo coronatum.
Semen obovatum. Integumentum crassum. Albumen ? tenue carnosum. * Embryo erectus.
Cotyledones ovales. Badicula infera.—Frutex ramis erectis, ramulis brevibus numerosis,
gemmis squamosis. Folia fasciculata simplicia S-dentata subtus albida. Flores terminates
conferti. Petala filamentaque siccitate ceruginosa.
1. P . tridentata. (T ab. LV III.) De Cand. in Linn. Trans, v. 12. p . 158, Prodr. v.
2. p . 541.—Tigarea tridentata. Pursh, FI. Am. v. 1. p. 838. t. 15.
Frutex erectus, cortice cinereo rugoso glabro tectus. Rami stricti subvirgati, ramulis brevibus fascicula-
tis onusti. Folia fasciculata semper e gemmis elongatis ramosis squamosis orta, 6-8 lineas longa, cuncata, in
petiolum brevem attcnuata, apice tridentata, supra glabriuscula, subtus albo-tomentosa. Stipulce minutse triangulares.
Flores solitarii vel congesti e fasciculis foliorum. Pedunculus brevis, glandulosus. Calyx extus
tomentosus, tubo elongato glanduloso glandulis pedicellatis, limbo 5-fido, patente, segmentis ovalibus, obtusis.
Petala 5, calyce inserta, laciniis alterna, patentia, obovata, obtusa, undulata, venosa, siccitate viridescentia,
basi in unguem attenuata. Stamina 25, ad orem tubi calycis inserta. Filamenta filiformia, siccitate sordide
viridia. Antheree subrotundae. Pistillum solitarium, ad basin calycis insertum, et ejus tubo duplo longius,
breviter stipitatum. Germen ovali-cylindraceum, pubescens atque glandulosum uni-ovulatum superne in
stylum attenuatum. Stigma lineare, laterale, pubescens. Capsula (seu Achenium) 6-7 lineas longa, cori-
aceo-membranacea, pubescens, ovata, basi apiceque attenuata, infeme calyce persistente tecta, indehiscens,
(longitudinaliter dehiscens, D C.) uniloculare, monospermum. Loculi paries longitudinahter striatus. Semen
obovatum, nigro-purpureum, prope basin loculi insertum dein erectum. Integumentum crassum, extus minute
punctatum: Parenchyma granulosum intense purpureum. Albumen camoso-membranaceum, albidum. Embryo
obovatus compressus carnosus albus. Cotyledones magnse, crassse. Radicula infera.
Hab. In the Prairies of the Rocky Mountains, and on the Columbia River. Lewis. “ Almost the only
shrub to be seen through an immense tract of barren sandy soil from the head sources of the Missouri to the
Falls on the Columbia, and from 38° to 48° of north latitude.” Douglas.—It does not appear that any
Botanist has ever gathered this highly interesting plant, except the travellers above-mentioned. From Lewis’
specimens of the Tigarea tridentata of Pursh, preserved in Mr. Lambert’s Herbarium, Professor De Candolle
established the genus Purshia in the Linnaean Transactions. - The figure given by Mr. Pursh is sufficiently
faithful for the general appearance of a branch; but the details of the fructification were still a desideratum.
This I have endeavoured to supply by the aid of the beautiful specimens collected by Mr. Douglas. The
covering of the seed presents an appearance which I do not quite understand. It is double. The epidermis,
which is thin and membranous, owes its colour to a deep purple granulated pulp lying between it and the
inner lining, which latter is opaque and fleshy, whence I have been led to consider it as albumen. The two'
coats are easily separated from the intermediate pulpy and granulated substance.
Tab. LVIIL Purshia tridentata. Fig. I, Flower from a gemma, natural size, with three leaves; fig. 2,
Flower not quite expanded, magnified; fig. 3, Expanded flower, with the gemma and leaves; fig. 4,
Section of a flower, some of the stamens and petals being removed; fig. 5, Back view of a stamen; fig.
6, Front view of do.; fig. 7, Pistil; fig. 8, Pistil laid open to show the embryo; fig. 9, Capsule with
its persistent calyx, natural size; fig. 10, Capsule, magnified; fig. 11, Capsule laid open to show the
position of the seed; fig. 12, Seed; fig. 13, Transverse section of do.; fig. 14, Embryo:—all but figs.
1 and 9, magnified.
4. SPIR® A. Lim. ,
Cal. 5-fidus persistens. Stam. 10-50 cum petalis toro calyce adhasrente inserta. Carpella
1-00, distincta, rariter basi coalita, brevi apiculata, sessilia raro stipitata. Sem. 2-6, suturse
internee affixa, exalbuminosa. Embryo inversus, cotyledonibus crassiusculis.— Frutices in-
ermes vel herbee perennes. Rami alterni. Folia alterna simplicia raro decomposito-pinnati-
secta, nervis pennatis vel ternato-palmatis. Flores albi aut rvbicundi nunquam flavi. DC.
S e c t . I. P hyso carpus. Camb.
1. S. opulifolia; foliis cordatis trilobis inciso-serratis petiolatis, corymbis hemispheericis
multifloris, pedicellis gracilibus longis, carpellis (3 v. 2) calyce triplo majoribus inflatis.
Linn. Sp. PL p . 702. Mich. Am. v. 1. p . 293. Pursh, El. Am. v. 1. p . 342. Elliott, Carol,
y. 1. p. 560. Torrey, FI. o f Un. St. v. 1. p. 482. De Cand. Prodr. v. 2. p. 542.— foliis
pedicellisque glabris, calycis marginibus solummodo pubescentibus.— S. opulifolia. «. Ser.—
p. foliis junioribus subtus pedicellis calycibusque pubescenti-tomentosis.— S. opulifolia. &■
tomentella. Ser.—S. capitata. Pursh, FI. Am. v. 1. p . 342. De Cand. Prodr. v. 2. p. 542.—
y . carpellis 2 pubescenti-tomentosis.— S. monogyna. Torrey in PI. o f Bock. Mount, p. 194?
Hab. a. Throughout Canada: from Lake Huron (Dr. Todd.') to the Saskatchewan. Dr. Richardson,
Drummond.—p. Fort Vancouver, (Mr. Menzies, Dr. Scouler,') and upon rocky banks of streams near the
Grand Rapids of the Columbia, Douglas.—y. Kettle Falls of the Columbia. Douglas.—The hairs of the
leaves on var. P. are beautifully fasciculated.
S e c t . II. C h a m a s d r y o n . Ser.
2 . S. hypericifolia ; foliis obovato-oblongis 3-4-nerviis integris vel dentatis glabris puber-
ulisve, nervis pinnatis, corymbis pedunculatis aut umbellis sessilibus, pedicellis glabris pu-
berulisve, sepalis adscendentibus. Ser.—Linn. Sp. Pl. p. 701. Pursh, FI. Am. v. 1. p. 341.
Torrey, FI. o f Un. St. v. 1. p. 480. De Cand. Prodr. v. 2. p . 543.—p. Plukenetia. Ser.
foliis integerrimis glabris, corymbis sessilibus.
Hab. . p. Canada. Pursh.—I am unacquainted with this, nor, though stated ■ on the same authority
to be found in the swamps of New York, has Dr. Torrey ever seen an American specimen. It is probable
that this, like so many of the species of this section, is exclusively a native of the Old World. The S. capitata,
placed here by M. Seringe, unquestionably belongs to the first section, and to S. opulifolia.
3. S. chamcedrifolia; foliis ovatis ellipticisve insequaliter serratis rarius sublobatis glabri-
usculis, corymbis hemispheericis pedunculatis, pedicellis lobisque calycinis reflexis pubescentibus.
Linn. Sp. Pl. p . 701. Pursh, FI. Am. v. 1. p. 343. De Cand. Prodr. v. 2. p. 542.—
p. foliis ellipticis obtusis glabris vel subpubescentibus.— S. chamaedrifolia. Pall. FI. Boss. p.
32. t. xv. (fig. med.)
Hab. North-West coast of America, (but surely not “ in Canada,”) Pursh.—p. Sledge Island in
Behring’s Straits. Mr. Menzies. Chamisso’s Island in Kotzebue’s Sound, ( Chamisso,) and on the mainland