Carnivorous Plants and Their Prey

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supplement their nutritional needs – these insects must be captured and thereby prevented from moving away – while concurrently attracting insects to transfer pollen from flower to flower or plant to plant – these insects must be allowed to escape the plant in order to ensure outcrossing (13, 41, 63, 64). This dual role becomes especially problematic when traps and flowers use similar attractants (13). In order to maximize both prey capture and insect pollination, carnivorous plants have a variety of mechanisms in place to limit pollinator consumption (12, 13, 63). Temporal Separation of Flowers and Traps The most practical way to separate potential prey from potential pollinators seems to be to separate the traps from the flowers (41). Several mechanisms exist to provide such separation. Carnivorous plants may differentially place their flowers and traps in time or space or they may separate traps and flowers by using different lures in an attempt to attract different visitors to each (10, 41, 63, 65). The oft studied Sarracenia provide several examples of temporal separation. In S. flava, prey-catching pitchers are not functioning while the plant is flowering (10). Studies of S. purpurea have shown this species to flower early in the growing season, often ahead of the production of pitchers. This reduces the likelihood of pollinating insects becoming prey (66, 67). The butterwort Pinguicula vallisneriifolia, too, has a flowering window in May and June just before carnivory intensifies in July (41). Early flowering, however, can be reproductively risky. Sarracenia purpurea may not flower every year possibly because late frosts sometimes kill developing buds before blooming can occur (8). The flowers may also appear before a reliable source of pollinators is available thereby precluding cross-pollination (67). Aside from simply keeping pollinators away from traps, carnivorous plants may time their flowering for other reasons as well. Carnivorous plants can maximize pollination by flowering when pollinators are most readily available – the more pollinators that may potentially visit flowers, the greater the likelihood of cross-pollination. Similarly, carnivorous plants may flower at given times to reduce competition for pollinators from other flowering plants (8, 44, 66, 28
67). Production of blooms when climate is conducive to efficient flower production and when pollinators are present in sufficient numbers may be as important as avoidance of overlapping the timing of flowers and traps (8, 66). For instance, some Drosera species appear to bloom for a very limited time. Drosera anglica flowers may be accessible to pollinators for only a few hours during a single day (44). Although this concentrates the number of floral visits by pollinators and increases the likelihood of out-crossing within in that narrow window, it could also result in missed opportunities to reproduce sexually, a potentially more costly situation than the loss of some pollinators to carnivory (44, 66). Another means of ‘collecting’ as many pollinators as possible over a short period of time may be mass, synchronized flowering of carnivorous species. This method of flowering may be especially important when pollinators are sparse or unreliable (66). Regardless of whether carnivorous species are using mass flowering or seasonal timing with respect to reproductive strategy, these mechanisms may provide a means to avoid direct competition with other anthophytes for limited pollinators. Darlingtonia californica, for instance, shares its habitat with several species of lilies, orchids, violets, and other wetland plants. Early flower production may be an effort to flower when sufficient pollinators are present but before competition for insects becomes too intense (66). Spatial Separation of Flowers and Traps Separation of traps and flowers may be accomplished by placing the two dichotomously functioning structures in locations that will increase the probability of collecting the appropriate organism (10, 41, 63, 66). Sarracenia purpurea, like many carnivorous plants, spatially places its traps well away from its flowers (10, 63). This species maintains relatively short pitchers and tall flowers (1, 11). Like their North American cousins, the tropical pitcher plants Nepenthes lowii and N. villosa also hold their flowers well above the traps (65). Two possible lines of thought are used to explain the placement of flowers above traps (41, 63). Research with Darlingtonia californica suggests this species constructs tall flowers to discourage pollinators from finding the traps. This would thereby limit competition between flowers and traps for the same resource – 29
Page 1 and 2: Carnivorous Plants and Their Prey,
Page 3 and 4: Carnivorous Plant Floral Design…
Page 5 and 6: capture prey; many others passively
Page 7 and 8: absorption of prey tissues near the
Page 9 and 10: order to obtain the nutrients (20).
Page 11 and 12: succession leads to woody plant gro
Page 13 and 14: Sticky leaf Rosette Drosera rotundi
Page 15 and 16: expense of carnivorous traps. A stu
Page 17 and 18: prey capture are generally recogniz
Page 19 and 20: The eminent end to the pitfall path
Page 21 and 22: Utricularia, and Polypompholyx (1).
Page 23 and 24: Pinguicula (35) - + + flypaper Trip
Page 25 and 26: such as butterflies, moths, flies,
Page 27: standing erect. Mature pitchers of
Page 31 and 32: hindered in their approach by direc
Page 33 and 34: ultraviolet patterns to attract pol
Page 35 and 36: plants (26, 41, 44, 45). Some carni
Page 37 and 38: plants, the loss of potential polli
Page 39 and 40: Table 3 - Examples of plant-animal
Page 41 and 42: While proteolytic bacteria may be c
Page 43 and 44: larvae within pitchers (38, 77). Al
Page 45 and 46: elease of nitrogen to the carnivoro
Page 47 and 48: S. darlingtoniae robs the carnivoro
Page 49 and 50: amounts of time traversing the leav
Page 51 and 52: insect prey (2, 10). Some ants are
Page 53 and 54: pitchers. Upon discovering a pitche
Page 55 and 56: Although carnivorous plants stand t
Page 57 and 58: 3. Conant, R. and J.T. Collins. 199
Page 59 and 60: 40. Thoren, L.M., J. Tuomi, et al.
Page 61 and 62: 72. Anderson, B. J.J.Midgley, and B

Carnivorous Plants and Their Prey

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