PEA AND BEAN TRIBE. 155 



prickly heads, which are both terminal and axillary ; 

 calyx-teeth unequal, very rigid, finally spreading ; 

 stems prostrate. Barren places, especially near the sea. 

 A small plant, with inconspicuous whitish flowers, and 

 remarkable only for its prickly calyces, especially when 

 in fruit. EL June, July. Annual. 



8. T. stridtum (Soft Knotted Trefoil). Flowers in 

 downy heads, which are both terminal and axillary ; 

 calyx rigid, furrowed, with straight, unequal, awl-shaped 

 teeth, swollen when in fruit ; stems ascending. Barren 

 places, especially near the sea ; common. Larger than 

 the last, with which it is often found growing. The 

 whole plant is covered with more or less silky hairs ; 

 the flowers are light purple, and the calyx is striated 

 with prominent nerves. El. June, July. Annual. 



9. T. glomeratum (Smooth Bound-headed Trefoil). 

 Flowers in round prickly heads, which are both ter- 

 minal and axillary ; calyx-teeth broad, very acute, re- 

 flexed ; stems prostrate. Gravelly places near the sea ; 

 not common. Yery similar to T. scabrum, but the 

 heads are rounder, and the calyx-teeth more leafy and 

 spreading. El. June. Annual. 



10. T. sulterraneum (Subterraneous Trefoil). 

 Flowers 3 5 together, in axillary heads, at first erect, 

 in fruit abruptly bent down, and sending out branched 

 fibres, which penetrate into the ground. Dry banks ; 

 not uncommon. A curious little plant, a few inches 

 long, with prostrate branched stems and white flowers, 

 which are remarkable for the above-named character of 

 bending down and, by the help of the altered calyx, 

 burying the seed in the ground while yet attached to 

 the plant. El. May, June. Annual. 



* To this group belong several other species of Tre- 

 foil, which are of local occurrence, and therefore not 

 likely to be met with by the beginner in botany. 

 T. stelldtum (Starry-headed Trefoil) occurs only near 

 Shoreham, on the coast of Sussex. It is distinguished 

 by the remarkably large calyx of the fruit, which spreads 



