4 86 
ODONTITES 
Odontites (Riv.) Hall. = Bartsia Linn. 0. serotina Dum. (0. vulgaris 
Moench) = i?. Odontites. 
Odontoglossum H. B. et K. Orchidaceae (28). 100 sp. Mts. of trop. 
Am. Epiphytes. Many are hot-house favourites. 
Odontospermum Neck. (incl. Asteriscus Moench). Compositae (iv). 
12 sp. Medit. O. (A.) pygmaeum O. Hoffm. is a curious little xero- 
phyte whose fruit-heads close in dry weather (cf. Anastatica, Mesem- 
bryanthemum) ; the seeds only escape in damp weather suitable for 
germination. 
Oenanthe (Tourn.) Linn. Umbelliferae (6). 35 sp. N. Hemisph., 
S. Afr., Austr. 7 in Brit, (water drop-wort). 
Oenothera Linn. (incl. Godetia Spach, Onagra Tourn., Xylopleurum 
Spach). Onagraceae (iv). 60 sp. Am. O. biennis L., the evening 
primrose, and many others, are favourite garden plants. The firs, of 
0. biennis emit their scent in the evening and are visited by nocturnal 
moths, to which they are adapted by their long tubes (p. 91). 
Oenotheraceae (Warming) = Onagraceae. 
Olacaceae. Dicotyledons (Archichl. Santalales). 25 gen. with 120 sp., 
trop. Most are shrubs or trees with small 5 firs. There is a distinct 
calyx, resembling the calyculus of Loranthaceae, but probably not 
equivalent to it. Petals 4 — 6. Sta. as many or 2 or 3 times as many. 
Ovary partly sunk in the disc, or free, 2 — 5-loc. at base, i-loc. above, 
with free placenta and 1 ovule hanging down into each loc. (occa- 
sionally it is 1 -loc. i-ovuled). Drupe or nut, one-seeded. Seed with 
testa and endosperm. Chief genera: Ximenia, Olax. Benth.- Hooker 
unite Icacinaceae to O. and place the order in Olacales ; Warming 
places it in Hysterophyta. 
Olacales (Benth.-Hooker). The 8th cohort of Polypetalae (p. 133). 
Olacineae (Benth.-Hooker) = Olacaceae -I- Icacinaceae. 
Olax Linn. Olacaceae. 30 sp. trop. Old World. 
Oldenlandia Linn. (excl. Hedyotis Linn.). Rubiaceae (1. 2). 80 sp. 
trop. Some are heterostyled (dimorphic). 
Olea (Tourn.) Linn. Oleaceae (1. 3). 30 sp. Medit., S. Afr., E. Ind., 
Austr. , Polynes. O. europaea L. is the olive tree, cultivated in the 
Medit. region from early ages. The wild form has thorny twigs and 
a small fruit, the cultivated form (var. sativa DC.) is smooth and has 
a large drupe with oily flesh. The oil is obtained by a process of 
bruising and pressing the fruit. Olive oil is now largely adulterated 
with cotton-seed oil, the oils of Arachis, Sesamum, Juglans, &c., 
imported into Italy for the purpose. 
Oleaceae. Dicotyledons (Sympet. Contortae). 21 gen. with 390 sp. 
trop. and warm temp., esp. E. Ind. They are shrubs and trees 
usually with opp. leaves, which are exstip., simple or pinnate, often 
entire. Serial accessory buds occur in the leaf-axils of many sp. ( e.g . 
Syringa) in both flowering and vegetative parts. The infl. is race- 
mose or cymose, often bracteolate. Firs. $ , rarely unisexual, regular, 
