PETALOIDE^:. 387 



tuberosa is the Tuberose, celebrated for its fragrance. The Butcher's 

 Broom (lluscus aculeatus) is remarkable for its ioliaceous peduncles and 

 really almost leafless stems ; and the fully developed flowering-stem of 

 Asparagus has only needle-shaped branches simulating leaves. 



More or less poisonous qualities pervade the Colchicum tribe (Melan- 

 thacese of some authors), with acrid, purgative, emetic, and sometimes 

 narcotic action ; several of the more active species yield valuable medi- 

 cines. Of Colchicum autumnale, called Meadow Saffron or Autumn Cro- 

 cus, both the corms and seeds are very active ; Veratrum album, White 

 Hellebore, V. nigrum, V. Sabaditta, V. viride (N. America), Asagrcea 

 officindis (Sabadilla or Csvadilla of Mexico), all share the acrid narcotic 

 qualities, poisonous or medicinal, according to the dose. Most of the other 

 genera are suspicious or dangerous, except perhaps the Uvalariece (N. 

 America), which are said to be merely astringent. 



XYRIDACEJE are sedge-like herbs with equitant leaves sheathing the 

 base of a naked scape, which is terminated by a head of perfect 3-androus 

 flowers, with a glumaceous calyx, a regular corolla, and extrorse anthers ; 

 the 3-valved, mostly 1-celled capsule containing several or many ortho- 

 tropous seeds, with a minute embryo at the apex of fleshy perisperm. In 

 habit these plants approach Cyperaceae ; but the flowers are petaloid as 

 regards the inner circle of organs, or corolla, nearly approaching Comme- 

 lynaceoe, from which they diner in having epipetalous extrorse stamens, 

 in the scaly calyx, and general habit. They are natives of the tropics or 

 adjoining regions. Various species of Xyiis are used as remedies for cuta- 

 neous aflections both in India and America. 



COMMELYNAOE^E (SPIDER-WORTS) are herbs with fibrous, some- 

 times thickened roots, jointed and often branching leafy stems, and chiefly 

 perfect and 6-androus, often irregular flowers, with the perianth free from 

 the 2-3-celled ovary, and having a distinct green calyx and a coloured 

 corolla, each of 3 parts, the calyx persistent ; stamens 6, all fertile or some 

 abortive, often very peculiar in form ; capsule 2-3-eelled ; seeds few (2) 

 in a cell, attached by a linear hilum ; embryo pulley-shaped, remote from 

 the hilum, in dense fleshy perisperm. Illustrative Genera : Commelyna, 

 Dill., Tradescanfia, L. 



Affinities, &c. This Order, to which belongs the garden Spider-wort 

 ( Trade scantia virginica),m.a,y be regarded as one of the groups intermediate 

 between the Orders with 6-merous glumoid perianth, like the Juncaceae, 

 and the petaloid forms like Liliaceae. The jointed solid stems of Tra- 

 descantia are interesting in regard to the comparative structure of Mono- 

 cotyledonous stems ; they emit roots freely from the nodes like Grasses. 

 The hairs of the filaments of the stamens of T. virginica are classic ob- 

 jects to the botanist, from the discovery in them of the rotation of the 

 cell-sap in non-aquatic plants. The rhizomes of Commelyna coelestis, tube- 

 rasa, and others contain starch and mucilage, and are used as food in 

 India. Some of the species are said to have medicinal properties. They 

 are natives of India, Australia, Africa, and the West Indies a few of 

 North America. Tradescant\a virginica is hardy in our gardens. 



PONTEDERACE^E are a small Order of aquatic herbs with perfect 

 more or less irregular flowers in a spathe ; the petaloid, 6-merous 



