533 piSTiACE^. [Levma. 



3. S. natans, L. Floating Bur-reed. " I-eaves floating plane, 

 common flower-stalk simple, stigma ovate very short, head of ste- 

 rile flowers mostly solitary."— /?r. Fl. p. 461. E. B. t. 273. 



In (liiclies, pouls, sluggish rivers and streams; very rare? Fl. July. Fr. Sep- 

 tember, Octdl.er. If, 



F. Med. — Verv profusely in the stream immediately above Aversion mill, but 

 never, I believe, fl(i-.vering there or in any of the running waters in the island, 

 however slow the current may be. lu the Medina and Yar, in aluindance, Mr. 

 Stiofike. 



IV. Med. — In some Utile pools (old chiy-pits) called, as well as I can ascertain, 

 Appey pools, on a small common a liitle E. of Cianmore farm, near Xingwood, 

 and which are nearly filled with Typha angusufolia, I found this species in some 

 plenty, August, IH40. 



The smallest ami slenderest of our three species. Root long, slender, creeping, 

 throwing out at intervals bundles ol white fibres and leaves. Stem round, smooth, 

 solid, very variable in length according to the deptli of water, floating or procum- 

 bent upon the mud or weeds about the margin, in which case or when the water 

 is shallow the whole plant does not exceed 6 inches in length. Leaves numerous, 

 sheathing, beautifully reticulated, very hmg, narrow (in my specimens barely Jth 

 of an inch wide), of a pale pellucid green, very thin, riband-like, olituse, perfectly 

 flat or keelless, by which tliis species may be immediately distinguished from the 

 barren floating form of S. simplex or S.ramosuin, so cnminon in our streams ; the 

 floral and one or two of the uppermost stem-leave<, which are partly above water, 

 are firmer and gieener than the lower submerged leaves. Heails o\ barren flowers 

 mostly scdilary. Heads ot fertile flowera generally two, seldom three, the upper 

 one quite sessile, the lower one ocrasionally on a short, pedmiele, each in the axil 

 of an erect short leaf, cimcave and inflated at the base, flat at the extremity, serv- 

 ing as a bract. Ovarie.i (gerraen^) in globular heads as in our other species, 

 ovato-coniual, obtusely angular. Stigmas ovato-oblong, obtuse and sessile. Seeds 

 (drupes) in globular heads like those of S. simplex, but far smaller, scarcely larger 

 than small peas or pist(d-hulk'ts. 



The transverse reticulation is far less conspicuous in the leaves of S. ramosum, 

 and probably also of S. simplex, than in the present species. 



The plant indicated as S. natans by Mr. Snooke 1 believe to be identical with 

 a floating form of what I take to be S. simplex, and which I find very abundantly 

 in the Medina, and in ditches on Sandown level, where there is a slow current. 

 As it does not produce floweis in this situation, there is some uncertainty about 

 the species. 



The French name, Rubanier, for this genus alludes no doubt to the floating 

 and riband-like leaves of S. natans. 



Order LXXXIV. PISTIACE^, Rich. 



"Perianth 0. Flowers 2, monoecious, enclosed in dispatha, but 

 not born on a spadix. — Sterile flowers solitary. Stamens 1 — 3 

 and distinct, or the filaments united, thick, and bearing 3 — 8 an- 

 thers. — Fertile floicers solitary. Ovary 1-celled, with 1 or more erect 

 or horizontal ovules. Style short. Stigma simple. Fruit some- 

 what membranaceous and indehiscent, or bursting transversely, 

 or baccate, 1- or more seeded. Seeds with a coriaceous thick 

 ribbed skin, and a thickened indurated /o9YKUcn. Embryo either 

 in the axis of a fleshy albumen and having a lateral cleft for the 

 emission of the plvmule, or at the apex of the micleus. Radicle 



