i88 9 .] 



BOTANICAL GAZETTE. 



they occur in countless numbers. Lying parallel with one 

 another they form compact bundles 'which are situated in 

 narrow elongated cells, known as crystal cells. The raphides 

 are very minute; in length from .01 mm. to .012 mm.; in 

 diameter about .002 mm. They are many sided, with angles 

 and faces poorly defined, and possess sharp ragged ends. 

 In addition to raphides, isolated stellate crystals are also 

 found in the fruit of Monstera. 



Concerning the early developement of fibres, de Barv 

 states that they arise by early outgrowth of a cell of the wall 

 of the cavity (usually one layer of cells thick), which remains 

 relatively narrow so as to form long, pointed arms. This 

 explanation may be accepted as general, but it has not been 

 satisfactorily proven in this special plant. 



Finally, we may draw the conclusion that since the raph- 

 ides are so minute, and form such a small quantity compared 

 with the fibres, and since the action of calcium oxalate is 

 very slight, the peculiar sensation caused bv placing a piece 

 of the outer fruit in the mouth must necessarily originate from 

 the mechanical action of the sharp-pointed sclerenchvmatous 

 fibres, and not from any chemical action of the raphides. 



Purdue University, Lafayette, Ind. 



Pi„? X « LA ? ATIO fr° F i P , LAT ? X — Fi S !• F ruit of Monstera deliciosa. 

 r lg. I. Section of fruit showing structure ; a, endocarp or core ; b, hexag- 

 onal segments or fruit proper ; x, mesocarp or edible portion ; y, exocarp. 

 1 %-t Exoc / r P Reeled under low power; a, libers, b, raphides. Fig. 



4. Fiber and raphides under high power. Fig. 5. Cross-section of " fruit 

 proper ; a, cross-section of fibre. Fig. 6. Longitudinal section of « fruit 

 proper ; a, crystal cell ; b, parenchyma cell ; c, fibre. 



Our worst weeds. 



BYRON D. HAL TED. 



It is due to those who have already aided me in the study 

 of the weed flora of the United States that some preliminary 

 report be given. The first twenty-five lists which have been 

 received contain in all 267 species, and represent 14 states, 

 ranging from Massachusetts to California, and Wisconsin to 

 Texas. As, in the present article, we are to deal with the 

 worst weeds, attention will be confined to those which ap- 

 peared at least live times in the lists. Of these there are 34 

 species, which will be enumerated below. 



