872 



STARCHES OF CRUCIFERACE^. 



STARCHES OF CRUCIFERACE/E. 



Class, Dicotyledones. Order, Papaverales. Family, Cruciferaceae. 

 Genus represented, Cochlearia. 



The CmdferacecB is a large family including about 175 genera and 1,500 species. 



GENUS COCHLEARIA. 



This genus is recognized by Warming, LeMaout and Decaisne, Joseph Hooker, and certain 

 other botanists as Cochlearia; by Gray as Radicula; by Britton as Roripa; and by Robert Brown as 

 Nasturtium. Cochlearia includes about 25 species, native of Central Europe, the mountainous 

 parts of the Eastern Mediterranean region, and the Arctic region. The best-known species in the 

 coimtry is C. armoracia Linn. {Nasturtium armorada Fries) , the common horse-radish ; its fleshy 

 roots are used as a condiment and contain much starch. C. officinalis Linn, is the scurvy grass, a 

 common perennial, chiefly European, that is eaten as a food and used as medicine. 



STARCH OF COCHLEARIA ARMORACIA. (Plate 97, figs. 581 and 582. Chart 3840 



Histological Characteristics. — In form the grains usually are simple. There are many compound 

 grains, some aggregates, and groups in which the dividing lines between the grains arc so wide that 

 they seem to be pseudo-aggregates rather than true aggre- 

 gates. There are a few surface indentations and also a 

 slight flattening of parts of some grains which might be 

 regarded as pressure facets, but there are no well-defined 

 facets. The conspicuous form is long, slender, regular 

 elliptical or lenticular with blunt or pointed ends. Forms 

 approaching the ovoid, a few round, and some irregularly 

 polygonal and hemispherical are also to be seen. The 

 two latter are formed from the others by the flattening 

 of the surface described above. 



The hilum is large, but never very distinct. In the 

 smaller rounded grains it appears as a round spot situated 

 centrally or slightly eccentrically, and in or near the me- 

 dian line. It may be marked by a fissure or line beneath 

 the surface of the grain, but which never communicates 

 with the exterior, and there is sometimes a depression of 

 the surface just above it. In the long forms the hilum 

 takes the form of a long line extending almost from one 

 end of the grain to the other and conforming more or less 

 to the shape of the grain. It is even and clear-cut and 

 has no subdivisions or ramifications; but sometimes in the long grains the hilimi is situated at one 

 end and an irregular fissure extends from it almost the length of the grain. There are no double 

 or multiple hila. 



The Umiellce are indistinct. When they could be distinguished, which was seldom, they appeared 

 to be coarse and regular, and numbered about 4 to 5 on the larger grains. 



The grains vary in size from 2 to 12/<; the common size is 18/^. 



Polariscojnc Properties. — The figure is usually centric, or slightly eccentric; it appears regular 

 and distinct, and is often clear-cut. Its lines may occasionally be bent and otherwise distorted, 

 and the bean type, consisting of one longitudinal line bisected at both ends, is not uncommon. 



The degree of polarization is fair to high. It varies in different grains and somewhat according 

 to the aspect of the grain. 



With seknite the quadrants are usually well defined, fairly regular in shape, and unequal in 

 size. The colors are not pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains are colored an intense indigo ; 

 with 0.125 per cent solution they color deeply. After heating in water until all the grains are com- 



Curve of Reaction-Intensities of Starch of Cochlearia 

 armoracia. 



