ENGELMANN — NORTH AM. SPECIES OF JUNCUS. 427 



axis, which often almost seem to constitute an umbel, but 

 which are mostly of very different length, the lowest ones 

 being by far the longest. These rays or branches often re- 

 peat the development of the main axis several times, or are 

 regularly dichotomously divided, or they assume the appear- 

 ance of one-sided spikes with lateral inflorescence, somewhat 

 after the fashion of the Borraginece. A remarkable example 

 of this is furnished by J. tenuis, var. secundus, which form 

 also proves that this uni-lateral development of the inflores- 

 cence can by no means constitute specific distinction, as a 

 series of intermediate forms are not wanting. We observe a 

 similar condition in J. Balticus and the var. Pacificus ; the 

 eastern form has the ordinary panicle, while that of the 

 Pacific coast bears on the branches uni-lateral flowers. 



In many others, and especially in all those that have knotted 

 leaves, the flowers are arranged in heads. These heads con- 

 sist of few, or are (often in J. pelocarpus) reduced to single, 

 flowers, or they bear a great many, and the different forms of 

 the same species often vary immensely in this respect. Thus 

 we find from 2 or 3 to 50 flowers in each head of the different 

 forms GtJ.pallescens, 6 or 9 to 100 in the forms of J. nodosus, 

 and 2 or 3 to 80 or 90 in J. Canadensis. These heads are 

 single, or composed of several heads crowded together, when 

 they appear lobed. I have seen the axis of the heads abnor- 

 mally elongated, thus chauging them into spikes 9-12 lines 

 in length in three different species, all found in the southern 

 States. In all of them the lower flowers seem to remain 

 sterile, and only the uppermost ones bear fruit; or, after the 

 earliest flowers have performed their functions, the axis, per- 

 haps in a wet season, continues to grow and produces a sec- 

 ond crop of flowers. J. cylindricus, Curtis, is such a spicate 

 form of</] marginatus / I have also seen it in J. pallescens, 

 var. fraternus, and most beautifully developed in J. Canaden- 

 sis, var. longicaudatus. In this last specimen numerous rays 

 form a rather compact almost level-topped umbel, and each 

 ray bears a head of 3 to 5 or 6 sessile, diverging spikes. The 

 heads are either single, terminating the stem like the head 

 of an Allium, or they form a more or less compound inflores- 

 cence similar to that of the single flowers. 



Flowers. — The flowers of these plants consist normally of 5 

 circles, each of 3 component parts ; 3 outer and 3 inner peri- 

 gonial leaves, which we call, on account of their herbaceous 

 texture, sepals ; 3 outer and 3 inner stamens and 3 carpellary 

 leaves; each of the circles alternating with the next one, so 

 that the 6 stamens stand before the G sepals, and the 3 

 carpels before the 3 outer sepals ; but the 3 stigmas, as well 

 as the valves of the capsule, before the 3 inner sepals. The 

 third circle, consisting of the 3 inner stamens, is some- 

 times wanting. Only in one instance, in the only species of 



[May, 1866.] 28 



