UMBELLIFERJE. 319 



very difficult to ascertain. I have, therefore, in the following Analy- 

 tical Key, endeavoured to lead to the determination of the species, as 

 far as possible, by more salient though less absolute characters, which 

 may suffice in a great measure for the few British species, although, 

 even for them, the minute variations of the fruit cannot be wholly 

 dispensed with. For this purpose it is essential to have the fruit quite 

 ripe. It must then be cut across, and if a horizontal slice is placed 

 under a magnify ing-glass, the general form, the ribs and furrows of the 

 pericarp, and the vittas, will clearly appear. Where the fruit is de- 

 scribed as laterally compressed, this slice will assume an oval form, the 

 division between the carpels being across the narrow diameter ; 

 where it is flattened from front to back, the division will be across the 

 broadest diameter. In Seseli and other genera, where the fruit is not 

 compressed, the horizontal slice will be orbicular. Where the albumen 

 is furrowed, its trausverse section will assume more or less of a half- 

 moon or a kidney shape. 



1 f Leaves undivided 2 



1 Leaves palmate or pinnate, or variously dissected 3 



r Leaves quite entire, grass-like or ovate. Flowers yellow 15. Bupleveb. 



2 <j Leaves rounded, crenate or peltate. Aquatic or marsh plant, with small 



L heads or whorls of flowers 1. Hydrocotyle. 



r Leaves and globular heads of flowers very prickly ... 4. Eryngo. 



3 <| Leaves and stems very thick and succulent .... 23. Samphire. 



L Leaves neither prickly nor fleshy 4 



r Fruit covered with prickles or bristles or hairs, or with dentate or sinuate 

 4*1 ribs 5 



L Fruit glabrous and smooth, or with entire ribs or wings 12 



- f Leaves orbicular or palmate. Umbels simple or irregularly compound 6 



1 Leaves pinnate or much dissected. Umbels usually compound ... 7 



r Flowers in small heads, without involucre. Fruit prickly . 2. Sanicle. 

 6-^ Flowers in simple or irregularly compound umbels. Involucre of many 



L bracts. Fruit rough, with sinuate or dentate ribs . 3. Astrantia. 

 i- J Fruit covered with bristles or prickles or hairs 8 



I Fruit glabrous, with sinuate ribs 35. Hemlock. 



R f Fruit flat, with a thick border 28. Hart wort. 



I Fruit ovoid, not bordered . 9 



q f Bracts of the involucre mostly pinnatifid 34. Carrot. 



I Bracts of the involucre entire or none 10 



{Umbels of more than 20 rays, with involucres of many bracts, and shortly 

 downy fruits 19. Seseli. 

 Umbels of few rays (seldom 10). Bracts few or none. Fruits burr-like 

 or very hispid 11 



f Fruit contracted at the top into a very short, smooth beak. 

 11 -| 32. Burr Chervil. 



l_Fruit covered to the top with hooked bristles . . . .33. Caucalis. 



