Francis E. Lloyd — 258 — Carnivorous Plants 



and South American species which are terrestrial. Their traps {28 — 

 7-9) are superficially much different from the vulgaris type, yet con- 

 form in having a short tube entrance, though this has a long funnel- 

 shaped approach, lined with numerous long-stalked glandular hairs. 

 The door, while lacking in well demarked mechanical areas, is ex- 

 tremely flexible because of very numerous constrictions in the inner 

 course cells (Lloyd 193 i). 



Biovularia has a door in which the middle piece is half its depth 

 (27 — 5, 6). At the upper edge of this there are always six tripping 

 bristles arranged transversely and radiating outwardly (Lloyd 1935a). 

 In U. purpurea and its allies (27 — 2-4) the tripping hairs arise in a 

 radiating manner from a tubercle centrally placed on the door which 

 is naked of other glands. Either the entrance is quite simple and 

 unadorned {U. purpurea) or the lower lip may be extended into a long 

 upturned rostrum carrying a few unicellular hairs, with a tuft of these 

 on each side of, but somewhat above, the middle of the entrance 

 {U. elephas Luetz.). The tripping hair consists of a long stalk {zg — 

 7), an elongation of an epidermal cell which is part of the tubercle, 

 expanded at the top, bearing a short basal cell, and a large mucilage 

 cell with expanded cuticle. The edge of the door is thickened by a 

 beading which rests in a slight depression of the narrow pavement 

 (Lloyd 1933a, 1935a; Luetzelburg) . The outer surface hairs are 

 sickle-shaped mucilage cells and sessile, oil-bearing ones (29 — 6). 



The mechanical response following a contact of prey against the 

 tripping hairs cannot of course be seen, but may be fairly guessed at. 

 Movement of the hairs causes slight rotation of the knob to which they 

 are attached. This results in slight displacement of the door middle 

 piece, disturbing the even contact of its edge on the threshold, thus 

 allowing the pressure of water to push it in. In a diagram {26 — 8) 

 I have shown the action (much exaggerated) as in the up and down 

 plane. The thinness of the door about the knob allows its rotation 

 (Lloyd 1933a). 



Traps with a long tubular entrance. — ■ The species belonging to this 

 group present a by no means homogeneous picture, and in some cases 

 are obviously less closely related to each other than those in the 

 short-tube entrance group. With regard to the mechanism of the 

 entrance they fall into two sub-groups: (7) That in which the door 

 when in relaxed posture presents along the sagittal axis a single con- 

 tinuous curve; and (2) that in which the door shows two curves, a 

 strong one in the upper hinge region, and a lesser one in the middle 

 piece. To the former belong U. cornuta (N. America) and caerulea 

 (Old World), the latter representing a large number of allied species. 



U. cornuta will serve as an example (jo — 1-8) . The trap is 

 wholly devoid of appendages. Just below the entrance there is a 

 rounded group of sessile glands (Schimper) which may be regarded 

 as a lure for prey. The tripping mechanism consists of a scattered 

 group of sausage-shaped glands on the lower half of the upper hinge. 

 They can be seen when one looks straight into the entrance. The pos- 

 ture of the door in the living trap in set and relaxed condition was 

 studied, and recorded photographically. In the set posture, the outer 

 selvage of the middle piece rests on the middle zone of the pavement. 



