CRUCIFER^ 83 



Erysimum hieracifolium L. 



A biennial species. Stem 1J-3 feet high, erect, stiff, angular, 

 simple or branched. Leaves oblong-lanceolate, entire or toothed, 

 with trifid hairs. Flowers bright or pale yellow. Lateral sepals 

 slightly inflated at the base, half as long again as the thick pedicel. 

 Petals small, spreading. Fruiting-spike dense. Seeds winged at 

 the top. 



Rocky mountainous places and roadsides. June. 



Distribution. — Almost all Europe from Norway to the Caucasus ; 

 Western Asia. Common in the East of France, but only occasional 

 in Switzerland. 



E. virgatum Roth, is a sub-species with linear-lanceolate and 

 usually entire leaves. 



In cultivation Erysima do best in ordinary loam in sunny places 

 on the rockery, and E. dubium is apt to die out on heavy soUs. 

 E. pumilum, a high Alpine species described in Alpine Plants of 

 Europe, is a dwarf plant which can be tightly wedged between two 

 stones in a hot, dry place with small bits of limestone scattered 

 round it. 



Thlaspi L. Pennycress. 



Annuals or low perennials. Leaves usually undivided, the upper 

 ones clasping the stem. Flowers small, white, mauve, or rose. 

 Petals equal or nearly so. Pod orbicular or obovate, flattened 

 laterally at right-angles to the narrow partition, the valves boat- 

 shaped, their midrib or keel more or less expanded into a green 

 wing surrounding the pod. Seeds two or more in each cell. 



A small genus spread over Europe, Northern and Central Asia, 

 and N.W. America, distinguished from Iberis by having more than 

 one seed in each cell of the pod, from all others by the winged pod. 



Thlaspi alpinum Crantz. 



Root fusiform. Stem simple, loosely csespitose, erect or ascend- 

 ing, 2-4 inches high, glabrous, like the entire plant. Leaves bluish 

 green, entire or toothed ; root-leaves spathulate and forming 

 rosettes ; stem-leaves ovate-lanceolate or lanceolate, cordate, 

 amplexicaul. Pods obcordate-lanceolate at base, narrow at apex, 

 I inch broad, narrowly winged, pointed at lower end, slightly 

 emarginate at the summit. Style prominent, filiform, 1-4 seeded. 

 Flowers white. Seeds smooth. 



Pastures and stony places in the calcareous mountains. June, 

 July. 



Distribution. — Eastern and Western Alps. In Switzerland near 

 Zermatt and possibly in Tessin. 



Not to be confused with T. alpestre L., which is very similar and 

 grows on limestone hills in Central and Western Europe and in 

 Northern England and in Somerset ; nor with T, montanum L., 



