A HISTORY OF HERTFORDSHIRE 



CARYOPHYLLE.* 



Silene noctiflora, L. 



Arenaria (Alsine) tenuifolia, L. 



LEGUMINOS/E 



Trifolium ochroleucum, L. 

 Astragalus hypoglottis, L. 

 Hippocrepis comosa, L. 



ROSACE.S 

 Poterium officinale, Hook. f. 



UMBELLIFER.* 



Bupleurum rotundifolium, L. 



Apium graveolens, L. 



Carum (Bunium) bulbocastanum, Koch 



Sesseli libanotis, Koch (Libanotis montana, 



CEnanthe Lachenalii, Gmel. 



Caucalis daucoides, L. 



VALERIANS* 

 Valeriana ofHcinalis, L. 



COMPOSITE 

 Antemaria dtoica, Br. 

 Senecio (Cineraria) campestris, DC. 

 Arctium majus, Schk. 

 Cnicus eriophorum, Hoffin. 



SCROPHULARINE.S 



Linaria spuria, Miller 

 Melampyrum cristatum, L. 



OROBANCHE^ 

 Orobanche major, L. 



LABIATVE 

 Ajuga chamxpitys, Sckreb. 



LORANTHACEJE 



Thesium linophyllum, L. (humifusum, DC.) 



ORCHIDEJE 

 Orchis ustulata, L. 



AunucEB 



Aftsma ranunculoides, L. 



NAIADACUI 



Potamogeton coloratut, Hornem 



GRAMINEJE 



Bromus racemosus, L. 

 Brachypodium pinnatum, Beauv. 



DISTRICT II. THE IVEL 



This district is south-west of that of the Cam, and is bounded on the north-west by 

 Bedfordshire and on the south by the Lea district. 



The Ivel rises near Baldock, leaves our county for Bedfordshire after a run of a mile and 

 a half, and is then soon joined by a longer stream rising near Wallington. Its next tributary 

 is the Hiz, which rises at Wellhead, a mile south of Hitchin (Hiz-chine), through which it 

 flows. A mile below Hitchin the Hiz receives the Purwell or Pirrall, a stream having a much 

 longer run than itself, and rising between Weston and Graveley ; and in another mile, at Ickle- 

 ford, it receives a small stream called the Oughton. Half-way between Bedford and St. Neots 

 the Ivel joins the Ouse, which pursues its course for some forty miles before it receives the 

 Cam near Ely. 



The Chalk downs of the eastern division of the Cam district are continued in a south- 

 westerly direction through the Ivel district, of which they form the north-western half. 

 Highest on the south-east, they slope downwards to the Gault plain on the north-west. Here 

 there are numerous combes in the Lower Chalk which have been formed by water issuing 

 from springs in the Totternhoe Stone. In most of them there is now no water and the soil 

 is particularly dry owing to the sinking of the plane of saturation of the Chalk, this portion of 

 the district consequently having an essentially xerophilous flora. 



Although this is a much larger district than that of the Cam, and its botany has been more 

 thoroughly investigated than that of any other, only half a dozen species are restricted to it. 

 Melampyrum arvense occurs only in one spot south of Ashwell ; Smyrnium olusatrum has been 

 found in one or two places north of Baldock and near Pirton, and there is also a record of its 

 occurrence at St. Albans in the Colne district, but its site has long been built over ; and the 

 other four species are confined to the neighbourhood of Hitchin. Of these Silene conica is the 

 rarest. The only record of its occurrence is near High Down, Hitchin, in 1875. 



The rarer plants of the district are 



RANUNCULACEJE 

 Anemone pulsatilla, L. 

 Ranunculus diversifolius, H. Wats. 

 Helleborus fcetidus, L. 



viridis, L. 



PAPAVERACEJK 

 Papaver hybridum, L. 



Lecocjii, Lamotte 



FUMARIACEJK 



Fumaria Boraei, Jord. 



parviflora, Lamk. 



Vaillantii, Lotsel. 



CRUCIFER.S 



Senebiera (Coronopus) didyma, Pennon 

 Iberis amara, L, 



