ill 





1 



The Structure of Cereal Straws 



2. S~^f 7 a 7 



By FRANCIS E. LLOYD, P.R.S.C. McGill University. 

 ( Rearranged and reprinted from the Pulp 'and Paper Magazine, Vol. XIX, pp. 953-4 Sept 15; 973-6 Sept 

 22; 1002-4, Sept. 29; 1025-6, 0c*. 6; 1048-50, Oct. 13; 1071- c 



General Summary. 



In the following' paper, the results of a study of the 

 structure of the four principal cereal straws have been 

 given. The purpose of this study was to determine (a) 

 the major differences in structure, especially as to the 

 character and length of the fiber, and (b) the possibility 

 of distinguishing the elements (cells) of each in a ma- 

 cerated product, or in a straw paper. 



In view of the variability and overlapping of char- 

 acters the latter task is not an easy one. The present 

 attempt was of necessity confined to samples of four 

 cereal straws supplied to the author. These embraced 

 only one race, doubtless an impure one, of each kind. 

 The findings were, however, checked by comparison with 

 pure, strain material (or nearly pure), with the result 

 that it became necessary to revise some of the conclu- 

 sions. This teaches that a thoroughgoing study of this 

 sort must embrace a large array of materials, failing 

 which the results must of necessity be to some extent 

 equivocal, and subject to revision. With this admission, 

 we are however permitted to say that it is possible by 

 careful inquiry, to determine the origin of the materials 

 in a given straw paper, or other straw-product, with 

 considerable certainty. 



Whatever the limitations, however, of this study, it 

 will serve to bring forward a basis for future ones in 

 the same field without being negligible with respect of 

 the amount and character of the information it con- 

 tains, which, in both regards, is certainly in measure- 

 able advance of the present available. The latter is 

 both meagre in quantity and often inaccurate in char- 

 acter. 



It is the purpose of the present paper to give an ac- 

 count of the structure of the "straw" of the barley 

 (Hordeum), oat (Avena) , rye (Secale), and wheat 

 (Triticum), based upon specimens from single local- 

 ities and of ordinary ripeness, or degree of develop- 

 ment (1). It will be understood that minor structural 

 differences, such as characterize various races of these 

 cereals, and even a single race grown in different local- 

 ities, are beyond our scope. Such differences may well 

 have to be considered in the event that the straw is to 

 be used for special purposes, but in any event they 

 would have to be investigated in relation to ' such pur- 

 poses. 



It is further important that the structure of the 

 straws of grasses shall be well enough understood so 

 that it is possible to distinguish the origin of the struct- 

 ural elements as they may be found in materials, such 

 as paper, manufactured therefrom; for it is easily pos- 

 sible that litigation may arise requiring such special 

 knowledge in its settlement. That this task is by no 

 means easy was the opinion of Wiesner (1910), who 

 has given much attention to the general subject of 'paper 

 materials. His conclusions, which indicate the difficul- 



ty j The specimens were supplied by Arthur D. Lit- 

 tle, Ltd., who also bore the major expense of the prepar- 

 ation of this work. The co-operation of the Forest Pro- 

 ducts Laboratory, especially through the valued assist- 

 ance of Mr. W. B. Stokes in the preparation of negatives 

 herein used, is heartily acknowledged. Mr. G. G. Moe 

 collected material for comparison at the Experimental 

 Farm, Ottawa. 



Oct. 20, 1921.) 



ties in some detail, are more specifically mentioned 

 beyond. It is believed that the evidence presented in 

 this paper is such as to show that Wiesner was not 

 wholly justified. 



What is "Straw?" 



By "straw" is meant the stems of mature cereals and 

 the remnants of various structures, especially of leaves 

 which may remain attached thereto. The term is also 

 extended to similar plants, such as esparto, when col- 

 lected for use. "Hay" is the same thing, but is cut 

 before maturity, so that there is a much larger amount 

 of food material in the stems and leaves, which are at the 

 same time less indurated, and in the immature grain 

 (seed). When cereals are cut as hay, the unripe grain 

 is left attached— barley hay, for example, — thus in- 

 creasing the food value. 



The straw that is obtained by machine threshing is 

 always more or less broken, and in any event the leaves 

 are shrivelled and more frequently torn away than other- 

 wise. Owing to the peculiar structure of the leaves 

 however, a part, namely the leaf-sheath, remains rather 

 tenaciously, as will be seen later. 



In reaping, the stems are cut off at about six inches 

 from the surface of the soil. About this length of stem 

 is therefore left behind, together with the parts (stems 

 and roots) which lie on or below the soil surface. In 

 this study, excepting only certain measurements of 

 stature, these parts are disregarded, since they do not 

 enter into any consideration of the usefulness of straw 

 as such. 



The Natural Affinities of the Cereals. 



The cereals or grain plants belong to a large and uni- 

 versally distributed group of plants known as the 

 grasses (Gramineae). It need hardly be said that these 

 plants are of fundamental economic importance, prim- 

 arily as food, and secondarily in manufacture, 'in ad- 

 dition to our own familiar grains, rice (Oryza sativa L.) 

 may be mentioned as of an importance as a food supply 

 equal to, if not greater than, all the other cereals taken 

 together, as a present economic fact. Indian corn, or 

 maize (Zea mays), sorghum, Kaffir corn ("durrha") 

 and sugar cane are other well known examples of prime 

 importance. In the Orient, young shoots of the bamboo 

 are used as a vegetable. A very great variety of grass- 

 es furnish grazing and hay, thus adding to a grand 

 totality of usefulness, which is discounted but little by 

 the fact that a very few grasses are poisonous. More 

 than usually interesting in this connection is the fact 

 that ergot, a highly poisonous but therapeutically use- 

 ful product of grains, is the hypertrophied grain (es- 

 pecially of rye), caused by the presence of a fungus 

 parasite, (Claviceps purpurea). 



Of possibly great economic importance in Canada is 

 the wild-rice (Zizania spp.) which furnished a staple 

 food for the Indians, and which offers an opportunitv 

 for extending cultivation to lands which cannot be 

 drained sufficiently for other agricultural purposes. 



As to other uses, the grasses furnish material for a 

 variety of purposes ranging from building to personal 

 adornment. In the tropical regions are found the giants 

 of the host, the bamboos, which more especially in the 

 Orient grow to large sizes (70 feet tall) inmany cases 

 and furnish an amazing variety of materials for use in 

 building, boat building, furniture making, and in the 

 making of an endless variety of smaller articles The 





