1 0 0 0 OA フラサバソウとオオイヌノフグリの生殖生態
ワラサバソウとオオイヌノフグリは百数十年、あるいはそれ以前に帰化した同属の類似種である。ワラサバソウの密な分布域は狭く、オオイヌノフグリとは対照的である。本報では両種の生殖生態を比較して、分布との関係を考察した。両種は自動的に自家受精した。また他殖も可能であった。単為結実はしなかった。筑紫野市原と、8 km離れた同市原田の自生群落(それぞれA、B群落とよぶ)で採取した両種の幼植物(A、B植物)を育て、袋掛けによって自殖種子S_A、 S_Bをえた。またA群落から放任採種した。さらにそれぞれ種内の人工交配によって他殖種子F_1(A×B)をえた。以下便宜上系統とよぶ。これら2雑草の各4系統を、それぞれラテン方格法で比較栽培した。生育量や種子生産数について、オオイヌノフグリでは4系統間に顕著な差はなかった。ワラサバソウでは、 S_A、 S_BはF_1(A×B)に比べ有意に少なく、近交弱勢を認めた。それ故、本種は1個体孤立して生じても、弱勢のために生存と繁殖ひいては定着に不利であろう。両種の自生群落で訪花昆虫を採集したところ、3目37種におよんだ。
- 著者
- 鶴内 孝之 古屋 忠彦 村山 祥子 島野 至 松本 重男
- 出版者
- 日本雑草学会
- 雑誌
- 雑草研究 (ISSN:0372798X)
- 巻号頁・発行日
- vol.33, no.3, pp.185-190, 1988-10-31
1 . lvyleaf speedwell plants were grown in four air conditioning rooms at constant temperatures under natural day length, from 1982 to 1983. In the 15℃ room, they formed a pair of opposite leaves on each of the lower 4 to 6 nodes of the stems, and then an alternate leaf and a flower on each of the upper nodes. In the 20℃ room, they formed opposite leaves on the lower 5 to 7 nodes, and then an alternate leaf and a flower, but fruiting was not prominent. In the 25℃ room, they developed only opposite leaves without a transition to alternate leaf arrangement. In addition, vegetative growth continued and no flowers was produced (Fig. 2) . In the 30℃ room, they did not grow and died within 1 or 2 weeks. 2 . Germinating seeds of ivyleaf speedwell were treated in a 4℃ incubator for 8 or 26 days, and young green plants of ivyleaf speedwell and birdseye speedwell were grown in at air conditioning box at 10℃ under diffused sunlight for 16 or 28 days, from 1984 to 1985 (Table 1) . Thereafter the materials were transferred to the 15, 20 and 25℃ rooms. The exposure of the germinating seeds to 4℃ and of the green young plants to 10℃ promoted the transition from opposite to alternate leaf arrangement, flowering and fruiting. The most remarkable results were as follows : the ivyleaf speedwell plants did not flower in the 25℃ room (Fig. 2), but the exposure to the low temperatures of 4℃ and 10℃ for 26 (VL) or 28 (GL) days, promoted the transition from an opposite to an alternate leaf arrangement, as well as flowering and in some cases fruiting (Table 2) .