486 PAPERS ON GENTIANEZ. 
found that it possesses a creeping, filiform rhizoma, 2-3 inches below the surface, from which at intervals filiform 
stems arise. These bear, at their thickened upper end, where they reach the surface of the soil, an undeveloped ter- 
minal bud of indefinite growth, and lateral annual flowering stems, the scars of which, enveloped by withered leaf- 
bases, can be traced sometimes for five or six years back. The vegetation of the plant is accomplished in the following 
manner. Each season the terminal bud develops two pairs of basal leaves ; from the axil of one of the outer leaves 
the single flowering branch originates. Inside of the two leaf-pairs just mentioned, we find a third and a fourth pair 
undeveloped, about half an inch long, which are to grow into the basal leaves in the following season ; and within 
’ these the four leaves of the next succeeding season, now only half a line long, are already preformed. The flower- 
ing branch, usually 3 or 4 inches high, normally bears one pair of Jeaves in the middle, and a second involucral pair 
just below the almost sessile flower ; the four sepals are opposite these four leaves, and the four corolla-lobes alternate 
with the sepals, and so on. In the axil of one of the third pair of basal leaves preparing for next year, usually alter- 
nating with, or sometimes opposite to, the present flowering branch, the bud of next year’s flowering apparatus is 
already four lines long ; it shows plainly the two pairs of leaves and the calyx, and, in a very rudimentary state, also 
the corolla, Thus each year’s vegetation exhibits at the flowering period (August and September), on the primary 
axis, two pairs of leaves for the present, two pairs for the next, and two for the third year, a secondary axis with two 
leaf-pairs and the flower, and another preformed secondary axis with the rudiments of the same organs for the next 
year. No other Gentian has, as far as I know, such a typical growth, with the regular preformation of all the organs ; 
but we find the same among other plants in other families, a striking example of which is furnished by our 
Nelumbium, The regularity in our Gentian is not as absolute as in Nelumbium ; for occasionally two flower- [195] 
ing branches are found on the same plant, or three pairs of leaves in place of two, or, very rarely, the upper 
involucral leaves bear one or even two axillary flowers. 
GENTIANA WISLIZENI, Engelm. l. c. pl. 7; Gray, Syn. 119. — Annual, erect, a foot or less high, with the habit 
and the many-flowered thyrsoid-paniculate inflorescence of the next; leaves from lanceolate to ovate, 1 inch or less 
long, with an obtuse or subcordate base ; calyx of barely half the length of the tube of the corolla, with very small 
teeth, its membranaceous tube cleft, and often, in age, dejected ; corolla pale purplish, 4-5 lines long, acute lobes 
fringed above the base; capsule linear ; seeds subglobose. 
White Mountains of Arizona, Rothrock (799), in 1874. This is the only known locality within our flora of this 
rare plant, which was discovered by Dr. Wislizenus over thirty years ago in the mountains west of Chihuahua. 
Gentrana AmARELLA, L., var. acuta, Hook. f. Gray, Syn. 118. G. acuta, Michx.— Annual, 2-20 inches 
high ; stems wing-angled, usually much branched; lowest leaves obovate, petiolate, upper ones lanceolate sessile ; 
inflorescence paniculate or strictly thyrsoid, with shorter erect or in some forms with elongated patulous peduncles ; 
calyx deeply 5-cleft ; herbaceous lobes lance-linear, somewhat unequal, often as long as the tube of the bluish-purple 
corolla, the lobes of which are oblong, obtusish, beset at base with copious (or in the diminutive alpine form, few) 
setee ; sessile capsule linear ; seeds subglobose. 
Grassy places in the mountains of Colorado and northeastward. The true European G. Amarella has usually 
4-parted flowers. 
HALENIA Ricupooxn, Gray, Proc. Amer. Acad. 11, 84; Syn. 127.— Annual, a span or two high, loosely 
flowered ; lower leaves small, spatulate, those of the stem distant, lance-linear, the uppermost closely approaching 
subverticillate ; flowers cymose-subumbellate, on slender peduncles, often in sevens, nearly 6 lines long, bright yellow, 
ovate, acute ion a little longer than the campanulate tube, the five spurs curved, horizontal or ascending, half as long 
as the corolla ; stamens from the throat of the tube ; anthers versatile ; seeds subglobose-ov. 
On Mount Graham, at 9,000 feet altitude; in ‘an in September, Rothrock (733), in ae ae [196] 
allied to three Mexican species which have also umbelliform cymes; the innermost involucral lea 
single flowers, the outer ones usually two, and a later secondary flower is borne on a shorter ahaa gree a pri- 
mary one. This is the only Western species yet discovered. Pirate XXI. Natural size. 1, Flower, 5 diameters. 
2. Mature capsule, cross-section, about 5 diameters. 3, Vertical section through flower, about 10 diameters. 
PLEUROGYNE? RoTATA, Griseb.; Gray, Syn. 124. Swertia rotata, L.—Stems 2-10 inches high, the smallest 
ones one-flowered, others thyrsoid-branched, many-flowered ; leaves lance-linear ; sepals linear, acute, as long as the 
milk-white @1 inch wide) corolla, acute at both ends. 
Moist, grassy places in Colorado, sometimes in large patches, and then disappearing again for years. The 
spreading (testi of this and the next two genera afford the best opportunity of observing the action of the versatile 
2 PLEUROGYNE, Eschsch. — Erect annuals of cold or al- 
a funnel- 
shaped crest or a fringed seale ; stamens versatile; ovary 
lanceolate, bearing the linear stigmas decurrent down the 
sides on the sutures ; ovules a on the broad placente 
on both sides of the on tures ; capsule oval, compressed ; 
seeds oblong, smooth. 
