Dr. Balfour's Botanical Excursion. 36 



at different times, we found a number of plants which deserve atten- 

 tion, such as Aquilegia vulgaris, Hesperis matronalis, Valeriana 

 pyrenaica, Campanula latifolia, Epilobium angustifolium, Polygonum 

 Bistorta, Prunus Padus, Lysimachia nemorum, Ruscus aculeatus, 

 Carex remota, and Scolopendrium vulgare. Somo of these species, 

 however, have undoubtedly escaped from the garden. Betula alba 

 and glutinosa were also seen. The latter is looked upon by most 

 botanists as a mere variety of the former, but Mr. Babington thinks that 

 ho has found a marked character in the stipules, which in B. glutinosa 

 are rolled back, while in B. alba they are circinnate. The form of 

 the fruit, ho also thinks, is different in the two cases. In a pond 

 near Ealabus grow Lycopus europsous, Potamogeton natans, and Nym- 

 phaea alba. On making a transverse section of the petiole of the 

 Nymph sea, it was observed that the large tubes had hairs in their 

 interior, which generally came off in threes. Again, in making a 

 similar section of the peduncle, or flower-stalk, we noticed generally 

 four or fivo large tubes in the centre, and smaller ones around, but in 

 none of them could any hairs be detected. These tubes in the stalks 

 of the flower and leaf appear to contain air for the purpose of floating 

 the various parts of the plant * Carex vesicaria and Equisetum limo- 

 sum both in an unbranched and branched state, were picked at Loch 

 Skiros. 



On examining some of the Carices and grasses, it was found that 

 the rule in regard to the solid stem in the former, and the hollow 

 stem in the latter, was not universal. Thus Carex remota and ovalis 

 had distinctly hollow stems, while Ammophila arenaria had a solid 

 stem. This grass is said by Dr. Parnell to be the only British one 

 with a stem always completely solid. t It also differs from other grasses 

 in not having a striated stem. It may also be remarked here, that in 

 the Umbelliferae, the character founded on tho fistular stem does not 

 invariably hold good, for on the same root solid and fistulose stems 

 will occasionally be found. 



Many of tho grasses in Islay displayed much of the ergot, or that 

 disease which is common in rye, and which is an altered state of the 

 ovary caused by the attack of a fungus, Ergotajtia abortifaciens of 

 Quekett This plant produces sporules, which communicate the 

 disease to healthy grain, either by being directly applied, or by being 

 taken up from the soil. Mr. Quekett has produced the disease artifi- 



* On examining the pedunolo of Nymphaa alba lately in Bute, I detected hairs in its 

 tubes as well as in those of the petiole. The same thing was seen in the peduncles and 

 petioles of Nuphar lutea. In the latter plant tho air-tubes in the petiole were larger 

 than those in the peduncle, and displayed the hairs most distinctly. 



t See Parnell's work on British Grasses. Bromus patulus, and some other foreign 

 grasses, have also solid stems, and Mr. Gorrie has noticed the same occurrence in some 

 varieties of wheat. 



