164 



KNOWLEDGE. 



May. 1911. 



mti Trst 



\\ I Htlu' 

 UIKIII 



It. 



microscope to show us the true knehness of each 



individual kind of hair. For there are very 



many different kinds, and each, in its \va\-, 



holds some, cliarm : some. too. 



show choice colours, others 



emit pleasant or disagreeable 



odours ; some produce oily or 



viscid exudations, whilst others 



form secretions with peculiar 



properties, such as hitter. (Priiu- 



ula sinensis). lemon\'. saltish, 



sugar\- and burning (stinging 



nettle). Some we find are very 



smooth-coated, others \er\- rough, 



whilst — internally — one hair may 



be built up of a number of separate 



cells, and another may consist 



of merelv one, long and narrow 



or broad and rounded as the 



case may be. 



If we look at an\' two hairs. 

 either is different from the other : 

 no twt) are ever quite alike, and 

 herein lies the absence of all 

 monotony. Each is an object of 

 itself : something trul\- marvellous, 

 the closest scnitin\' w u (-an bestow 



Amongst the man\- different 

 kinds met with, the following 

 are the principal :— 1 1) Forked, 

 (_') Hooked, (3) Glandular, (4) 

 Branched. (5) Stinging, (6) Stel- 

 late, (71 Peltate, (8) Jointed, 

 though, perhaps, those known 

 as Root-hairs should be con- 

 sidered chief of all, since the\- 

 are, truly, the means hv which 

 a plant derives its food from 

 the soil in which it grows, and 

 is able to perform its life's func- 

 tions. They are the most useful, 

 though their li\'es arc \-erv brief, 

 and, at the same time, some of 

 the most simple in form that 

 can be met with an\where. 



I. — Forked and Hooked 

 Hairs. 



Forked, or. as the\" are also 

 called, barbed hairs are often 

 extremely curious as well as 

 beautiful in form and are \er\" 

 frequently met with on plant 

 surfaces. Their distinctive feature 

 is, that the hair pedicel, or stem, 



terminates in two or more prongs which are some- 

 times thick and rounded at the tips, but mcjst 

 often ver}- sharp-pointed : sometimes, too. the\- 

 are quite erect in position, whilst at others they 

 become curved. 



Some quaint examples nia\' be seen in the 

 accompanying illustrations. Figure 1 shows forked 



FiGl'KE 2. 



Forked Hairs from ihu Skin 

 ol the Gardi-ii .Auhrclur. 



d those that. 



Fork. 



hairs found on the blossom of vegetable-marrow. 

 It ma\- be noticed that the hair consists of a 

 number of thick cells placed one on top of the 

 other till quite a long pedicel is 

 formed, and then that the pedicel 

 di\-ides off into twd thick 

 branches, or prongs. In the 

 smaller hair illustrated, it will 

 be seen that the [)rongs are 

 being formed. 



Figure 3 represents barlied 

 hairs that abound on the leaves 

 of our Wild Rough Hawk-bit. 

 Each prong will be seen to be 

 very sharp-pointed. Figure 2 

 is a specially prett\- example of 

 a three-pronged hair from the 

 stem of Aubretia. a plant so 

 fa\oured in our rock-gardens 

 and rock edges of borders. 

 The \\a\- ill which the sharp 

 prongs spread out from the tip 

 of a somewhat short, thick stem, 

 is ver\- suggestive of a fork. 

 Hooked liairs are also known as curved or 

 iw-likc. and are found largel\- on climbing plants 

 whilst not being in the true 

 sense climbers. straggle up 

 hedgewa\s, and in and out 

 of the Luidergrowth of copses. 

 The\- are \er\ useful to such 

 plants, for the\' act as small 

 .L^r.ippling irons and readih' catch 

 oil to an\' foreign suppoits. 



Figure 4 shows cur\-ed hairs 

 found on the leaf of the garden 

 scarlet-runner bean. They are 

 lieautiful little structures and 

 most usctul as climbing supports, 

 tiny though they are. Figure 6 

 represents the saw - like hairs 

 h)und on e\er\- surface, stem, leaf 

 and Hower of wild Cleavers; a 

 plant that grows in rank luxuri- 

 ance in most of our hedges 

 and copses ; a " weed "' that 

 often causes great annoj'ance by 

 the persistent wa\' in which it 

 clings to one's own clothing 

 when wandering along the 

 countrxside. Strange, indeed, are 

 the hooked hairs met with on 

 ^\ild Hop (see Figure 5). another 

 climbing plant of English hedge- 

 rows. On stem and leaf these 

 curious hairs abound, and one needs only to see 

 their formidable appearance to understand why 

 it is that in wet weather (when the hairs are 

 specialh- stiff), if hop - picking, or wandering 

 carelessly between the hanging sprats in a hop- 

 garden, one's skin becomes so terribl}' torn: the 

 hooked hairs are rea]l\- able to tear and cause great 



Figure 3. 



d Hairs from the Leaf of 

 KouKh Hawk-bit. 



