62^ CELLULAR TISSUE. 



examples of the latter may be named the smalJ hairs of Vcrbascum \ the thin-stalked stars 

 of Lavendula Stoechas, &c. Also the short stalked, two- to many-armed hairs of 

 Utricularia ■' and Aldrovanda ^, in which each arm is a blunt cylindrical cell, belong partly 

 to this category, partly to the tufted hairs to be named below. 



Hairs not forked, but monopodially branched, are (if we disregard cases like that 

 described in Loasa) always pluiicellular. Thus those with scattered, and sometimes 

 repeatedly branched arms in Nicandra physaloides (IMeyen, Weiss, /.c), Lavendula 

 elegans, Rosmarinus officinalis (leaf), on the inner surface of the bud-scales of Platanus 

 (Hanstein, I.e.), those with whorls of branches on the leaves of Lavendula vera, species of 

 Verbascum (e. g. V. phlomoides, the larger hairs). Also those demonstrated by Schleiden*, 

 \vhich cover the leaf of Alternanthera spinosa, belong to this group. Not only is the lower 

 ])art, which is attached to the foot, composed of 4-5 disk-shaped cells, one above another, 

 but also the upper richly branched part is composed of as many cells as it bears whorls of 

 main branches. The cells are separated from one another by transverse walls folded in 

 deep waves, and each bulges out immediately above the transverse wall, which limits it 

 below, into a whorl of pointed branches, and here and there, on the rest of the lateral 

 wall, into a single branch. The form often cultivated as Alternanthera amoena shows 

 the same structure in its scattered hairs, but with only weak development of the 

 branchlets. 



The bodies described by Weiss (/. c, Fig. 76) as branchlets on old hairs of Verbesina 

 gigantea, I was unable to find either in this plant, or in a member of the same genus, and 

 cannot make anything of them. 



Under the name of tufted hairs, already often used, Weiss has judiciously separated a 

 form allied to those under consideration from the forms usually included in the term 

 'stellate hairs.' It arises by the division of an initial cell of a hair by a number of 

 successive w-alls perpendicular to the epidermal surface, and each of the cells thus 

 produced grows like a simple conical hair, the body of which diverges from the others, 

 while the basal parts remain firmly united. The history of their origin justifies the 

 position of these bodies here, side by side, with the branched, pluricellular hairs, though, 

 as far as the mature state is concerned, one might just as well speak of a tuft of diverging 

 simple hairs. The tufted hairs are either seated in the epidermal layer, or are borne by 

 a thin stalk-like emergence (e.g. feity species of Solanum, as S. marginatum, verbasci- 

 folium, species of Correa), or on the apex of a multiseriate shag-hair (therefore a 

 transitional form) ; this is the case in many Melastomeae (Tetrazygia elaeagnoides ^, 

 discolor, angustifolia). Further examples are furnished by very many (all ?) Malvaceae '' 

 Cistineae ; among the Labiatae, Marrubium ; species of Croton, e. g. Cr. tomentosus, 

 J. Mull ; species of Quercus, Platanus (comp. Weiss, Rauter, I.e.). The single rays of a 

 tuft are usually unicellular, in INIarrubium pluricellular. 



2. Capitate hairs : erect hairs of various forms, whose free end is swollen to form a 

 round or disk-shaped head, the transverse section of which usually exceeds that of the 

 stalk. The head may be part of a cell, or of a unicellular hair (Fig. 21, B, d, glandular 

 hair of Aspidium molle) ; or it may be itself a single cell (Fig. 31-34), or be 2- to multi- 

 cellular, with the cells arranged in the most various ways in one or several layers one 

 above another. Capitate hairs are in the large majority of cases simple. Branched ones 

 are only known where certain branch-endings of ramifying conical hairs bear a head 

 (hairs of the bud of Platanus '''). The stalk bearing the head may be reduced to a 

 minimum, to the form of a very small disk — e, g. the glandular hairs of many Labiatas 

 (Pogostemon, Plectranthus, Molucella, &c. ; Fig. 2 1, A, b, e, 38). 



* Weiss, /. c. fig. 1 84. 



^ Meyen, I.e.; Benjamin, Botan. Zeitg. 1848, p. 58; Schacht, Bcitrage, p. 28. 

 2 Caspar}', Botan. Zeitg. 1859, p. 128, Taf. IV. 



* Grundz. I. 3 Aufl. p. 280. * Rudolphi, Anatomie, p. 113, 

 ' Compare Sachs, 2nd Eng. Ed. pp. 43, loi. '' Hanstein, I.e. fig. 96. 



