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Rh etc.; the lady's traces (Spiranthes autumnalis), Denham, etc.; Epipactis violacea, Amersham, etc.; Orchis militaris in chalk woods; O. incarnata, Chalfont; O. latifolia, Uxbridge, etc.; the daffodil (Narcissus Pseudo-narcissus), Chesham, etc.; the snowflake (Leucojum æstivum), by the Colne; the Solomon's seal (Polygonatum multiflorum), Chalfont, etc.; lily of the valley (Convallaria majalis), Alderbourne; the garlic (Allium ursinum); the snake's head (Fritillaria meleagris), near Iver; the herb Paris (Paris quadrifolia), Chesham, Denham, etc.; the rushes Juncus squarrosus, Fulmer; Juncoides Forsteri, Chesham; the reed mace (Typha angustifolia), Fulmer; the sweet flag (Acorus), Langley, Wraysbury, etc.; the lesser water plantain (Echinodorus ranunculoides), Iver Heath, Hyde Heath; the wood club rush (Scirpus sylvaticus), Alderbourne; the white beak-rush (Rynchospora alba); the sedges Carex axillaris, C. pallescens, C. pendula, C. binervis, C. Pseudo-cyperus, C. vesicaria; the grass Apera Spica-venti, plentiful about Colnbrook and Drayton; the foxtail (Alopecurus fulvus), Chalfont; the purple melic (Molinla varia), Iver Heath; the grasses Catabrosa aquatica, Denham, etc.; Bromus interrupts, Denham; Nardus stricta, Fulmer; Elymus europteus, Chenies, etc.; the black spleenwort (Asplenium Adiantum-nigrum), Chalfont; ''A. Trichomanes, Denham; the sweet mountain fern (Dryopteris montana = Lastrea Oreopteris), near Chalfont; the adder's tongue (Ophioglossum vulgatum), Colnbrook, etc.; and the club-moss (Lycopodium inundatum''), formerly on Iver Heath, but now probably extinct.

The district of the Colne includes a larger number of introduced species than any other of the districts, as its contiguity to the metropolis would lead us to expect. Among the plants which although not strictly native are now well established are Bromus arvensis near Amersham; B. secalinus, common in corn crops; Erysimum cheiranthoides, plentiful in arable fields in the lower parts.

But the most prominent alien is the North American balsam (Impatiens biflora or fulva), which now borders the Colne and its ramifying branches from Denham downwards, and not content with the main streams has followed the watery ditches and even occupied the damp ground near, but giving withal a touch even if of bizarre beauty in the rich colour of its blossoms. Another North American species is the monkey-flower (Mimulus Langsdorffii), which is most abundant by the Chess between Latimers and Chenies, and also by the Misbourne from Great Missenden downwards. The cress Lepidium ruderale is also established about Iver, where the rubbish heaps are covered with a rank growth of the chenopodiums already mentioned, as well as with Datura Tatula and D. Stramonium, Melilotus arvensis and ''M. alba''; and the two latter also occur near Amersham. The tomato (Lycopersicon esculentum) is a common plant, as the seeds can germinate after passing through the alimentary canal, but the plants do not survive the late autumn frosts. The sweepings of seed shops are responsible for the canary grass (Phalaris canariense), the millet (Panicum miliaceum), and P. Crus-galli (with and without awns), Setaria viridis and S. glauca, the flax (Linum usitatissimum), the hemp (Cannabis sativa), and the buckwheat (Fagopyron esculentum), but there are others the origin of which it is more difficult to account for; one especially interesting is Atriplex littoralis, a marine plant which is very abundant. There also have been found Lepidium Draba, Lactuca Scariola, Sisymbrium Sophia, Solanum nigrum in varying forms, as well as Lepturus incurvatus, Medicago denticulata, Briza maxima, Vicia lutea, V. Villosa, Melilotus indica, Phalaris aquatica, and Setaria italica. From other parts of the district Verbascum Blattaria, Sedum Cepæa, S. reflexum, S. album, Delphinium Ajacis have been recorded. The spleenwort (Asplenium fontanum), which Hudson recorded from Amersham church, is no longer found, and of course it was never native there.

The very picturesque pine woods and heathy ground of Black Park contain boggy ground as well as heathy soil, and it is the only home of one or two species such as Carex Itevigata, C. canescens, but the latter is very rare, if not extinct. Here too occur the small skullcap (Scutellaria minor), the creeping scorpion-grass (Myosotis repens), the shore-weed (Littorella), the sweet chestnut (Castanea sativa), seeding freely, the hawkweeds, Hieracium boreale, H. sciaphilum and H. umbellatum, the marsh violet (Viola palustris), and the bog-bean (Menyanthes).

Part of this estate was probably included in the Iver Heath as mentioned by the eighteenth century botanists.

For Buckinghamshire and the six bordering counties of Berks, Oxon, Middlesex, Herts, Beds and Northants about 1,100 well established species have been recorded; of these there have been recorded for Buckinghamshire 934 species. Space will not allow of giving each of the 167 missing species in detail, but the more important absentees may be noticed. These are