(ENOTHERA 



599 



OIDIUM 



CE. sero'tina (late- flowering') . ij. Yellow. September. 



N. Amer. 1820. 

 serrula'ta (small- toothed), i. Yellow. June. N. 



Amer. 1824. 



specio'sa (showy), i. White. June. N. Amer. 1821. 

 ma'jor (larger). 6. White. July. N. Amer. 

 tanacetifo'lia (tansy-leaved). See CE. NUTTALLII. 

 taraxacifo'lia (dandelion-leaved). See CE. ACAULIS. 

 tetrago'na (iour-angled-poddfd). See CE. FRUTICOSA. 

 Utra'ptera (four-winged), i. White or blush. July 



to September. Mexico. 

 ro'sea (rosy). Rosy, with darker veins. 



HARDY BIENNIALS. 



CE. a'lbicans( whitish). 2. Whitish. June. Peru. 1823. 

 biSnnis (biennial). 4. Yellow. July. N. Amer. 1629. 



" Common Evening Primrose." 

 grandiflo'ra (large-flowered). 2-4. Very large, 



yellow. July to September. 

 bi'frons (two-faced). See CE. AMCEXA. 

 crucia'ta (cross-flow ered). See CE. BIENNIS. 

 ela'ta (tall). 2. Yellow. July. Mexico. 1824. 

 ero'sa (jagged). 2. Citron-coloured. July. S.Africa. 



1828. 



globula'ris (globular). 3. Yellow. July. 1824. 

 grandiflo'ra (large-flowered). See CE. BIENNIS GRANDI- 



FLORA. 



hi'rta (hairy). J. Yellow. August. N. and S. Amer. 



1836. 



,, inca'na (hoary). See CE. FRUTICOSA. 

 lamarckia'na (Lamarckian). See CE. BIENNIS GRANDI- 



FLORA. 

 longifto'ra (long-flowered). 3. Yellow. August. 



Buenos Ayres. 1776. 



,, me'dia (intermediate). See CE. FRUTICOSA. 

 noctu'rna (night-sm//tng). 2. Yellow. July. S. 



Africa. 1790. 

 odora'ta (sweet-scented). 2. Yellow. June. S. Amer. 



1790. 

 vire'scens (greenish). 2. Yellow. June. S. Amer. 



1790. 

 pube'scens (downy), x. White. July. S. Amer. 



1825. 



salicifo'lia (willow-leaved). See CE. ELATA. 

 simsia'na (Sims' s). 3. Yellow. July. Mexico. 1816. 

 stria'ta (streaked). Yellow. July. 1822. 

 vtilo'sa (shaggy). 2. Yellow. July. S. Africa. 1791. 



HARDY ANNUALS. 



CE. albe'scens (whitish), ij. Purple to white. June. 



Columbia River. 1841. 

 amce'na (pleasing). 2. Purple. July. N. Amer 



1825. 

 rubicu'nda (ruddy). Lilac-purple, with four 



blotches. California. 1834. 

 vino'sa (claret-coloured). White, with four purple 



splashes. California. 1835. 

 ,, berteria'na (Berterian). Chili. 

 bisto'rta (twice- twisted). i. Yellow. Summer. 



N.W. Amer. 

 veitchia'na (Veitchian). $-1. Yellow, with four 



blood-red spots. S. California. 

 dava'ta (club-leaved), i. White. July. Mexico. 



1827. 

 conci'nna (neat), i-it. Pink. July to September. 



Chili. 

 corymbo'sa (corymbose). 2-3. Yellow. August, 



September. Mexico. 1816. 

 decu'mbens (lying-down). i$. Purple. August. 



California. 1827. 

 densiflo'ra (close-flowered). 3. Purple. August. 



California. 1830. 

 denta'ta (toothed), i. Yellow. August. N. and S. 



Amer. 1837. 

 humifu'sa (prostrate). Pink. Steins flat on the soil. 



N. Amer. 

 Johnso'ni (Johnson's). 2-3. Citron-yellow. July, 



August. N.W. Amer. 1898. 

 le'pida (pleasant). See CE. DECUMBENS. 

 Li'ndleyii (Lindley's). See CE. AMCENA. 

 minutiflo'ra (minute-flowered), i. Yellow. July, 



August. Chili. 1837. 



ova' fa (egg-shaped). Yellow. July, August. Cali- 

 fornia. 



CE. pinnati'fida (deeply-lobed). White. July. N. Amer. 



1811. 



,, purpu'rea (purple) of Bentham. See CE. ALBESCENS. 

 purpu'rea (purple) of Curtis, i. Purple. June, 



July. N. Amer. 1794. 

 Pu'rshii (Pursh's). See CE. PINNATIFIDA. 

 quadrivu'lnera (four-blotched). i-i. Pink, with 



four crimson spots. N. Amer. 1826. 

 Romanzo'wii (Romanzow's). i-ij. Purple. June 



to August. N. Amer. 1817. 

 sinua'ta (scoHoped-leavett). 3. Yellow. July. N. 



Amer. 1770. 

 mi'nima (smallest). J. Yellow. July. N. Amer. 



1825. 



stri'cta (erect). See CE. STRIATA. 

 tene'lla (slender). *. Purple. June, July. Chili. 



1823. 

 tenuifo'lia (thin-leaved). it. Purple. August. 



Chili. 1828. 

 tri'loba (three-lobed). *. Yellow. June. N.W. Amer. 



1822. 



vimi'nea( twiggy). 2. Purple. July. California. 1826. 

 ,, vino'sa (claret-coloured). See CE. AMCENA. 

 virga'ta (rod-shaped), ij. Purple, white. July. 



Peru. 1823. 

 WhitnSyi (Whitney's). iJ-2*. Rosy, with four 



crimson blotches. J uly, August. Columbia River. 



1831. 

 Williamso'ni (Williamson's). 1-2. Western United 



States. 



OFFSETS are side bulbs produced by some bulbous 

 roots, and by which the species can be propagated. 

 Whatever checks the upward growth of the parent plant, 

 as an early breaking down of the stem, compels the sap 

 to find other organs for its reception, and, consequently, 

 promotes the production of offsets. " The practice," 

 says Dr. Lindley, " of scarring the centre of bulbs, the 

 heads of echino-cacti, and such plants, and the crown of 

 the stem of species like Aga've geminiflo'ra, in all which 

 cases suckers are the result, is explicable on the fore- 

 going principle." 



(yFTIA. (Derivation not clear. Nat. ord. Myo- 

 poraceae.) 



Evergreen shrub for the greenhouse. Cuttings of half- 

 mature shoots in sand, covered with a bell-glass in 

 summer. Loam, leaf-mould, and sand. 

 0. africa'na (African). 2-3. White. July. S. Africa. 

 1710. 



OGEECHEE LIME. Ny'ssa Oge'che. 

 OfflGGI'NSIA. See HOFFMANNIA. 



OHLENDO'RFFIA. (Commemorative of Dr. C. F. 

 Ollendorff, of Holstein. Nat. ord. Scrophulariaceae.) 



A small greenhouse shrub now generally referred to 

 Apto'simum depre'ssum. Seeds ; cuttings of half-mature 

 shoots in sand under a bell-glass. Fibrous loam and 

 peat in equal proportions and sand. 

 0. procu'mbens (lying-down). 1-2. Blue. July, August. 

 S. Africa. 1836. 



OIDIUM. The name given to a group of allied fungi 

 that attack the leaves, flowers, fruits, and other parts of 

 plants. They appear to the naked eye as a white coat- 

 ing covering the parts of plants affected, and are generally 

 known amongst gardeners and farmers as mildew. Under 

 the microscope they are seen to consist of an interlacing 

 mass of jointed filaments or fine threads, sending small 

 rounded suckers into the tissues of the plants affected, 

 and by means of which they absorb food to the great 

 injury of the host-plants. Other branches of the fungi 

 grow erect, forming rows of globular, barrel-shaped, or 

 cylindrical cells (conidia), which fall off at maturity 

 and spread the fungus on healthy plants with remarkable 

 rapidity. The conidial form is merely the earlier stage 

 of various higher fungi. Two of the most common are 

 Oidium Balsamii, on turnips all over Britain, and O. 

 Tuckeri on the grape vine, both under glass and out- 

 doors. The higher stage of this latter is Uncinula 

 spiralis, bearing numerous spirally coiled filaments on 

 its perithecia, which are the fruit-producing bodies, and 

 contain ascospores. Other well-known fungi of the group 

 are Erysiphf graminis, on grass ; E. Martii, on peas ; 

 Microsphara grossularice, on gooseberries; Spharoiheca 



