264 
B1C0RNES 
Bicornes (Warming). The 1st cohort of Sympetalae (p. 137). 
Bidens (Tourn.) Linn. Compositae (v). 90 sp. cosmop. 2 in Brit, 
(bur-marigold). The fruit is animal-distributed by aid of the 2-6 
barbed bristles of the pappus. B. Baku Torr. (N. Am.) is a water- 
plant with two kinds of leaves (p. 163). 
Biebersteinia Steph. Geraniaceae. 4 sp. Orient. 
Bifrenaria Lindl. Orchidaceae (18). 10 sp. trop. S. Am. 
Bigelowia DC. Compositae (ill). 34 sp. N. Am. 
Bignonia (Toum.) Linn. (incl. Cremastus Miers, Cydista Miers, Dox- 
antha Miers, Paragonia Bur., Phaedranthus Miers, Pleonoioma 
Miers, Pyrostegia Presl., Stizophyllum Miers, all regarded as in- 
dependent genera by Schumann in Nat. PJB). Bignoniaceae (1). 
150 sp. Am., mostly lianes. In B. Tweediana Lindl. the tendril is 
grapnel-like with three sharp claws. The stem twines, and both 
petioles and tendrils are sensitive to contact. When either curves 
round the support, the claws catch hold of their own stalk or the 
stem as they come round. After clasping the tendril thickens and 
becomes woody. In B. capreolata L. the tendrils are bluntly hooked 
and show great negative heliotropism. When the tip enters a crevice 
it forms a ball of parenchyma, secreting cement (cf. Vitis). Then 
the free part contracts spirally and becomes woody. Several sp. are 
cultivated for their showy protandrous firs. 
Bignoniaceae. Dicotyledons (Sympet. Tubiflorae). About 60 gen. 
with 500 sp. trop. There are no sp. and only one genus (Catalpa) 
common to the old and new worlds. Most occur in Brazil ; a few 
are found in temp, regions. They are trees and shrubs, most com- 
monly lianes, with opp. usually compound exstip. leaves. A con- 
siderable number are xerophytic shrubs with condensed stems, but 
the chief interest of the order centres in the climbers, which form a 
very important feature in the forest vegetation of S. Am. There are 
twiners (e.g. Tecomaria, Pandorea), root-climbers ( Tecoma radicans ), 
and tendril climbers (most B.). In Eccremocarpus &c. the inter- 
nodes and petioles are sensitive, but in most B. the tendrils are at 
the ends of the leaves (in place of leaflets, as in Vicia). The tendrils 
are frequently branched : in some cases, e.g. Bignonia, the branched 
tendril occupies the place of one leaflet. Three types of tendril are 
found — simple twiners, tendrils provided with adhesive discs (as in 
Virginia creeper), and hooked tendrils. See Glaziovia, Bignonia &c. 
The climbing stems exhibit many features of anatomical interest, 
owing to their peculiar growth in thickness (p. 173). 
Infl. usually dichasial with cincinnal tendency (p. 52); bracts 
and bracteoles present. Fir. g , zygomorphic, hypogynous. K (5) : 
C (5), usually bell- or funnel-shaped, descendingly imbricate; A 4, 
epipetalous, didynamous, the anther-lobes usually one above the 
other, the posterior staminode always present; G (2) on hypogynous 
disc, 2- (or rarely 1-) loc., with oc erect anatropous ovules on axile 
