Stigma Behavior And Pollination In Three Species Of Bignoniaceae With Bilobed Stigma

The biologic characteristic of the bilobed sensitive stigma is the hot question on the flowering plants research. The bilobed sensitive stigma is common in Scrophulariaceae, Bignoniaceae, Martyniaceae and Lentibulariaceae. What is the mobile feature of the sensitive stigma and whether is the same in different plants remain unclear up to now. Three common plants with the bilobed sensitive stigma in the Bignoniaceae were selected in this research: Campsis radicans, incarvillea arguta and incarvillea sinensis var. sinensis. A series of observation and research on the biologic characteristic of the three plants have been conducted in order to make it clear that the stigma behavior and the pollination biologic characteristic of the sensitive stigma are in Bignoniaceae: 1 .What is the flower structure characteristic of the bilobed sensitive stigma is in Bignoniaceae, 2.What is the basic mobile feature of the bilobed sensitive stigma in Bignoniaceae, 3.The relationship between the pollination characteristic and the stigma behavior of the three plants with bilobed sensitive stigma in Bignoniaceae. Till now we have gotten some answer to the above questions.The basic mobile rule of the sensitive stigma and the flower structure in the three genus are the same, similar to the Mimulus aurantiacus: long, tubular corollas; four anthers, two long, protandrous, hermaphrodite, when the flower opens, the anthers have dehisced, but the stigma will spread some time later; one sensitive stigma with two thin splinters, which will close to the mechanical or pollen touch, the stigma closing to mechanical touch all will reopen in a short time, but just some of the stigmaclosing to the pollen touch will reopen in a long time, the stigma will always be open if not been touched; fruits with much seed.There are some difference between the detailed mobile rule of the stigma and the pollination biologic characteristic in C. radicans, I. arguta and /. sinensis var. sinensis. In this three plants, /. arguta and /. sinensis var. sinensisis is more similar. The central difference about the stigma motion is the time how long the stigma will be closed to the mechanical or pollen touch. The stigma of C. radicans will close in 40-150 seconds after mechanical touched while close inl5-105 seconds after pollen touched, and the closed stigmas to the mechanical touch all will reopen half or one hour later, while only a few closed stigmas to pollen touch will not reopen during the following time, most will reopen 1 to 3 hours later. The stigma closing to mechanical or pollen touch in /. arguta and /. sinensis var. sinensis are faster than that in C. radicans, the time the stigma reopen needed is shorter: the stigma of /. arguta will close in 5-73 seconds (mostly in 20-40 seconds) after mechanical touched while close in 4-52 seconds (most inlO-20seconds) after pollen touched, the closed stigmas to the mechanical touch all will reopen in 15-48 minutes, only a few closed stigmas to pollen touch will reopen in 25-95 minutes; the stigma of/, sinensis var. sinensis will close in 8-70 seconds(most in 20-35 seconds) after mechanical touched while close in 3-24 seconds after pollen touched, the closed stigmas to the mechanical touch all will reopen in 14-30 minutes, a few closed stigmas to pollen touch won't reopen in following time while the other closed stigmas to pollen touch will reopen in 21-87 minutes. When the flower faded, there are most flowers with the open stigmas in C. radicans, more in /. arguta, much in /. sinensis var. sinensis. The stigma closing permanently in C. radicans need most pollen grains (>350), and in /. arguta need more pollen grains (about 200), in /. sinensis var. sinensis need much pollen grains (about 100).The difference between productive biologic characteristic in C. radicans, I. arguta and /. sinensis var. sinensis lies to the following: The corolla is biggest, the P/O and the pollen is most, the stigma is longest in C. radicans; all is middle in /. arguta, and all is the least in I. sinensis var. sinensis. But the self or cross pollinatedfruit set in C. radicans is lowest, is lower in /. sinensis var. sinensis, and is highest in /. arguta. C. radicans is complete self-sterile following pollinated by pure self-pollen. But /. arguta and /. sinensis var. sinensis are self-compatible.From the mobile rule of the stigma and pollination biologic characteristic, we can deduce that: the bigger the corolla is, the longer the stigma is, the more the pollen is, the slower the stigma reaction is. The pollinatior difference between the three plants is related to their stigma behavior. The corolla of C. radicans is bigger, and its main pollinator is bees and hummingbird; the corolla of /. arguta and /. sinensis var. sinensis is smaller, their main pollinator is ants. Such matching can make the pollinator move easily in the corolla, but not touch the stigma freely.The biologic meaning of the sensitive stigma three plants are different: the stigma behavior in C. radicans aiding pollen capture and receipt, preventing alike floral pollination to prevent the genus decline is a mechanism facilitates pollination; the stigma behavior in /. arguta and /. sinensis var. sinensis can aid pollen capture and receipt to facilitiate pollination; prevent intrafloral selfing to prevent the genus decline.