Passiflora biflora

P. biflora is one of the most common species of Passiflora in second growth and edge habitats at La Selva. The two-lobed leaf shape and the nectaries on the leaf blades are distinctive. The nectaries are attractive to egg parasitoids and ants. The stems are slender, flexible and strong, and have 6-8 longitudinal ridges. Range: Mexico to Ecuador and Venezuela. P. biflora is widespread in Costa Rica. P. biflora is one of 120 species belonging to section Decaloba, subgenus Decaloba. The only other local member of this section is rare at La Selva and is found in the higher elevations, P. lancearia.

P. biflora foliage is slightly to strongly cyanogenic when crushed (0.2 to 10 μM/g HCN per gram tissue). According to Spencer (1988) P. biflora contains the cyclopentenoid cyanogens Passibiflorin and Epipassibiflorin. It is interesting to note that larval growth rate measurements at controlled temperatures showed Decaloba-specialist H. erato growing about 10% faster than the Passiflora generalist H. cydno when feeding on P. biflora (Smiley 1985a). Perhaps erato is able to use the cyanogenic glycosides as nutrients, as proposed for H. sara feeding on P. auriculata. HCN measurements on P. biflora rootlets from three different plants indicated substantially lower values than in the foliage (.032-.112 μM/g), a 90% reduction not seen in other Passiflora species at La Selva (with the possible exception of P. pittieri).

H. cydno, H. hecale and especially H. erato lay their eggs on P. biflora at La Selva, the former species on the tendril tips and the latter laying single eggs on the shoot tips among the incipient leaves. The rare species H. hecalesia has also been seen laying eggs on this plant altough it is known to prefer P. lancearea as host. The heliconiid Dryas iulia also lays eggs on the new leaves.

This species is also eaten by several species of flea beetle, including the generalist Blue Flea Beetle (Monomacra violacea), the Yellow-legged Flea Beetle (Parchicola DF2), the Red-black Flea Beetle (Monomacra chontalensis), and the Red-brown-white Flea Beetle (Ptocadica bifasciata). The Yellow-tibia Flea Beetle (Parchicola "Yellow-tibia") has been observed on P. biflora, along with the rare (at La Selva) Striped Flea Beetle (Disonycha quinquelineata). I have also found leaf-feeding larvae of D. quinquelineata on P. biflora at La Selva.

I confined Parchicola DF2 and Monomacra chontalensis in experimental cages with potted P. biflora for 2-3 months, on three separate occasions, but no reproduction occurred. I may have had too few individuals (3 of unknown gender) of M. chontalensis for a fair test.

Measurements of HCN production in P. biflora foliage show many patterns of variation among leaves. One branch that was growing in shade appeared to be actively withdrawing HCN capacity toward the roots from the newer leaves. Another, vigorously growing plant showed a variable response to leaf damage which disappeared after 48h. As compared with P. auriculata, P. biflora is 5-10 times more cyanogenic, and shows more within-plant variation in cyanogenesis. (See Figure 5).
P. biflora leaves are quite variable in shape and color, even more so than is found in other Passiflora. The lobes can be very long and thin, and there may be variegated coloring on the lobes.
 Flower are small and mostly white.
Paired flowers are characteristic of the P. biflora species group.
 Dipteran leaf miners are tiny. The membranous leaves are very thin.
Egg-mimetic flower buds
 Tiny flower buds often look like butterfly eggs.
Yellow leaves can be very attractive! Red-brown-white Flea Beetle Ptocadica bifasciata and Blue Flea Beetle Monomacra violacea on biflora leaf.
Narrow-lobed P. biflora. Red-black Flea Beetle (Monomacra chontalensis) on P. biflora stem. P. biflora is a preferred host for adults of this species.
Yellow-legged Flea Beetle (Parchicola DF2) feeding on P. biflora. Disonycha quinquelineata? larva on P. biflora. This reddish species of flea beetle is rare at La Selva but widespead elsewhere - usually on P. biflora.
H. erato larva feeding on P. biflora stem. Adult Disonycha quinquelineata on P. biflora.
Dryas iulia larva on P. biflora leaf Disonycha quinquelineata larva on P. biflora stem. Note the tiny droplets tipping the spines when you enlarge the photo (click on photo to enlarge)
Graph showing HCN release at 20 second intervals. Note the unusual quick burst at about 60 seconds for the mature leaf. The later burst at 100 seconds is more typical of Passiflora.
 
P. biflora HCN release over time. This time profile is typical of most Passiflora I have tested and probably represents a system with enough β-glucosidase enzyme to cause release in the first 5 minutes.  
Evidence that P. biflora withdraws HCN capacity from foliage. The trigger for this is unknown, but this plant was growing in shade. Also, the branch was cut off between leaves 13 and 15 and returned to lab for measurement. The rest of the branch was cut off the next day after leaf 27.
P. biflora growing rapidly in partial shade. Leaves were sampled by plucking and taking them to the lab. No evidence of HCN induction caused by plucking leaves!
This plant was growing vigorously in full sun. Note peak quantities of HCN in newest foliage.
This plant was growing vigorously in the lab garden. Leaves were sampled by cutting the tip from one lobe, and further damaged with 5 1cm cuts into the leaf. After 24h many of the damaged leaves exhibited changed HCN capacity, including about a 50% increase in the two youngest leaves. In contrast, the alternate, undamaged leaves exhibited no change. By 48h, the changes had dissappeared.