FAMILIES OF PLANTS 53 
rather abundantly. For this reason they are listed prominently 
among plants that cause hay fever. 
Greasewood (Sarcobatus vermiculatus) .—This is a somewhat spiny, 
rigidly branched shrub with linear, fleshy leaves and it grows mostly 
in moist, saline flats. It is quite common in the vicinity of the 
Gardiner Eiver north of Mammoth Hot Springs. It grows 2 to 5 feet 
high and has smooth, white bark. The leaves are pale green, some¬ 
what three-angled, and 1 to 2 inches long. The flowers are imperfect, 
the staminate borne in close terminal spikes and the pistillate solitary 
in the leaf axils. 
Spiny hop-sage (Grayia spinosa) is a smaller shrub, 1 to 2 feet 
high, with small, somewhat fleshy leaves, and is found in the same 
locality as the greasewood. 
Strawberry-blight (Blitum capitatum) is a fleshy, branched, annual 
herb that is found in moist mountain valleys. It grows 8 to 20 inches 
high and is smooth throughout. The alternate leaves are more or less 
arrowhead-shaped and usually sharply toothed. The small flowers 
are produced in axillary, headlike clusters which are often half an 
inch in diameter and become bright red, somewhat resembling berries. 
Monolepis nuttcdlAana reminds one of strawberry-blight but it 
grows only 4 to 8 inches high and is not fleshy. Also the leaves are 
usually entire or nearly so. 
Other members of the family that have been identified in the park 
are Lambsquarters (Ghenopodium album), G. aridum , C. atrovirens , 
C. conardii , C. fremontii , G. glaucum , G. Mans , C. humile , G. lepto - 
phyllum , G. murale , G . salinum , Molly (KocMa americcma) and 
Russian thistle (Salsola pestifer) . These are all weedy plants and not 
very important. 
TOUR O’CLOCK FAMILY (NYCTAGINACEAE) 
This family contains many plants with beautiful flowers and some 
of them are extensively cultivated as ornamental plants. The beauty 
of the flowers in this case, however, is due largely to the calyx which 
is colored like a corolla since the flowers have no corolla. It is some¬ 
times due also to an involucre that surrounds the flowers. Some 
members of the family open their flowers late in the afternoon and 
close them the next morning, and the family gets its name from this 
habit. Yellow sandverbena ( Abronia ammopMla) , which is found on 
the sandy shores of Yellowstone Lake, is probably our only repre¬ 
sentative. It is a prostrate plant with stems 8 to 16' inches long and 
is more or less glandular and sticky throughout. The oblong or 
elliptic leaves are opposite and the two leaves of each pair are some¬ 
what unequal in size. The greenish or creamy-yellow flowers are 
quite numerous, both axillary and terminal, and usually quite fra- 
