GENUS 33. 



MUSTARD FAMILY. 



181 



7. Arabis hirsuta (L.) Scop. Hairy Rock- 

 cress. Fig. 2075. 



Turritis hirsuta L. Sp. PI. 666. 1753. 



Arabis hirsuta Scop. Fl. Cam. Ed. 2, 2: 30. 1772. 



Arabis ovata Poir. in Lam. Encycl. Suppl. 5: 557. 1817. 



Stem strictly erect, nearly simple, i-2 high, rough- 

 hairy or nearly glabrous. Basal leaves on margined 

 petioles, obovate or spatulate, obtuse, dentate or repand, 

 i '-2' long; stem-leaves sessile, clasping by an auricled 

 base, lanceolate or oblong; pedicels nearly erect, or ap- 

 pressed, 3"-6" long in fruit ; flowers 2" -3" long, white 

 or greenish-white ; petals more or less longer than the 

 calyx; pods narrowly linear, erect or appressed, i'-2' 

 long, about \" wide; seeds i-rowed, or when young ob- 

 scurely 2-rowed, oblong or nearly orbicular, narrowly 

 margined ; style very short. 



In rocky places, New Brunswick to Yukon, British Co- 

 lumbia, south to Georgia, Missouri, Kansas, Arizona and 

 California. Also in Europe and Asia. May-Sept. 



8. Arabis glabra (L.) Bernh. Tower Mustard or 

 Cress. Fig. 2076. 



Turritis glabra L. Sp. PI. 666. 1753. 



Arabis glabra Bernh. Verz. Syst. Erf. 195. 1800. 



Arabis perfoliata Lam. Encycl. i : 219. 1783. 



Biennial, erect, glabrous and decidedly glaucous above, 

 pubescent at the base, nearly simple, 2-4 high. Basal leaves 

 petioled, 2'-io' long, oblanceolate or oblong, dentate or some- 

 times lyrate, hairy with simple pubescence, or with hairs at- 

 tached by the middle; stem-leaves sessile, with a sagittate 

 base, glabrous, entire or the lower sparingly dentate, a'-6' 

 long, lanceolate or oblong, acutish ; pedicels 2" -6" long, erect ; 

 flowers yellowish-white, 2" broad; petals slightly exceeding 

 the calyx; pods narrowly linear, 2'-3' long, i" wide, strictly 

 erect and appressed ; seeds marginless ; style none. 



In fields and rocky places, New Brunswick to southern New 

 York and Pennsylvania, west to the Pacific Coast. Appears in 

 some places as if not indigenous. Also in Europe and Asia. May- 

 Aug. 



9. Arabis laevigata (Muhl.) Poir. Smooth Rock-cress. Fig. 2077. 



Turritis laevigata Muhl. ; Willd. Sp. PI. 3 : 543. 1801. 

 A. laevigata Poir. in Lam. Encycl. Suppl. i : 41 1. 1810. 

 Arabis laevigata Burkii Porter, Bull. Torr. Club 17: 



15. 1890. 

 A. laevigata laciniata T. & G. Fl. N. A. 1 : 82. 1838. 



Glaucous, entirely glabrous, i-3 high, nearly 

 simple. Basal leaves petioled, spatulate or obo- 

 vate, sharply and deeply dentate, or sometimes 

 laciniate, 2'-$' long; stem-leaves sessile, lanceo- 

 late, or the upper linear, acute, entire or dentate, 

 usually clasping by an auricled or sagittate base; 

 pedicels ascending or spreading, 4"-s" long in 

 fruit; flowers greenish white, 2"-3" high; petals 

 nearly twice the length of the calyx or less ; pods 

 3'-4* Icng, i" wide, recurved-spreading; seeds in 

 i row, oblong, broadly winged ; style almost none. 



In rocky woods, Quebec to Ontario, South Dakota, 

 Georgia and Arkansas. April-June. 



Arabis serotina Steele, found at Millboro, Vir- 

 ginia, differs in being widely branched, its narrower 

 leaves not clasping, its flowers smaller, appearing in 

 August. 



Arabis viridis Harger, a recently proposed New 

 England species, differs in being green, more leafy, the pedicels erect in flower, the petals longer. 



