AZOLLA 
256 
node, from the dorsal half of a segment of the apical cell ; from the 
ventral half are formed roots and branches, but not. at every node. 
The leaves are all alike ; each is bilobed and has a small cavity near 
the base, opening to the outside by a small pore, and inhabited by 
the Alga Anabaena . The roots hang freely down in the water; 
usually the root cap is thrown off after a short time and the root 
comes almost exactly to resemble the submerged leaf of Salvinia. 
The sporocarps are formed in pairs (4 in A. nilotica ) on the ventral 
lobes of the first leaves of the branches. Each contains one sorus. 
The microspores are joined together into several masses in each 
sporangium by the hardened frothy mucilage (epispore, cf. Salvinia). 
Each of these massulae has its outer surface provided with curious 
barbed hairs ( glochidia ), and escapes from the sporangium on its own 
account. The megasporangium contains one spore. It sinks to the 
bottom and at length decay of the indusium frees the spore and it ger- 
minates, giving rise to a female prothallus which floats about on the 
water and may be anchored to a floating massula by the barbs. 
Azorella Lam. Umbelliferae (1). 35 sp. S. temp. Densely tufted 
xerophytes. A. caespitosa Vahl. is the balsam-bog of the Falklands, 
forming tufts like Raoulia (cf. Ternetz, Bot. Z., 1902, p. 1). 
Babiana Ker-Gawl. Iridaceae (hi). 30 sp. S. Afr. , Socotra. 
Baccaurea Lour. Euphorbiaceae (A. 1. 1). 50 sp. W. Afr., E. Ind., 
Polynesia. 
Baccharis Linn. Compositae (ill). 300 sp. Am. Some are leafless 
xerophytes with winged or cylindrical green stems (Bot. Jb. 27, 446). 
Backhousia Hook, et Harv. Myrtaceae (2). 5 sp. Austr. B. citriodora 
F. Muell. gives an essential oil consisting almost entirely of citral, 
the valuable ingredient in citronella oil. 
Bactris Jacq. Palmae (iv. 7). 90 sp. S. and Cent. Am. Firs, in 
groups of 3, one ? between two <? . B. minor Jacq. is the pupunha 
or peach palm, grown in Brazil for its edible fruit. 
Baeckia Linn. Myrtaceae (2). 60 sp. Austr. to China. 
Baeria Fisch. et Mey. (excl. Actinolepis DC.) Compositae (vi). 
20 sp. Calif. 
Bahia Lag. Compositae (vi). 12 sp. W. Am. 
Balanophora Forst. Balanophoraceae. 11 sp. Indo-mal. Some are 
apogamous (cf. Filicineae, Angiospermae, and see Treub in Ann . 
Buitenz. xv). 
Balanophoraceae. Dicotyledons (Archichl. Santalales). 15 gen. with 
40 sp., all but one trop. Parasites on tree roots, to which the tuberous 
rhizome is attached by suckers (p. 176). From it springs the infl. 
(sometimes developed within the rhizome and breaking through it), 
which comes above ground as a spike or head with scaly leaves and 
small unisexual firs. For details and figures see Nat . Pfi ., or Kerner’s 
Nat. Hist, of PL Chief genera: Scybalium, Balanophora, Langs- 
dorffia. [Placed in Achlamydosporeae by Benth.-Hook., in Hystero- 
phyta by Eichler (Warming).] 
