Lee B. Kass

On the light requirement for replication of plastids in polytrichum

Abstract The chloroplasts of germinating spores of the moss Polytrichum replicate in darkness to a lesser extent than in light. A stable number of plastids is attained by 48 h in darkness, i.e. the plastids become light-dependent with respect to replication. Light stimulates the plastids to replicate. When red light is used, the promotive effect of the light can be completely reversed by far red light.

Distribution of androdioecious and hermaphroditic populations of the mangrove Laguncularia racemosa (Combretaceae) in Florida and the Bahamas.

The breeding system of Laguncularia racemosa is variable among populations; some populations are androdioecious while other populations lack male plants. To determine whether androdioecy is widespread in L. racemosa , 65 populations were surveyed in Florida and the Bahamas. Fruits are water-dispersed, so the observed distribution of breeding systems was compared to local and regional water currents in order to determine whether dispersal could be important to the maintenance of male plants in androdioecious populations. Twenty-two of the 36 populations surveyed in Florida were androdioecious, with male frequencies that ranged from 1–68%. On the Florida east coast, all populations north of latitude 26°30′ N lacked males while all populations south of this latitude were androdioecious, which suggests that northern populations may lack males due to dispersal limitation. The pattern of distribution on the Florida west coast suggests that males may be maintained in some populations via dispersal. Nine islands in north-central Bahamas were surveyed, and androdioecious populations were found only on San Salvador Island, where male frequencies ranged from 5–28%. Dispersal, fragmentation, and selection hypotheses are suggested to explain the observed pattern of distribution; these hypotheses will be tested in future studies.

The effect of darkness and inhibitors of protein synthesis on the replication of chloroplasts in the Moss, Polytrichum

Abstract The replication of chloroplasts in Polytrichum spores and germlings occurs to a more limited extent in darkness than in light. After 48 h of darkness a stable mean number of plastids per spore or germling is attained. Brief exposure to light permits further replication, which can occur in the light or darkness. Thus it appears that a response to light triggers a series of events that can continue in darkness. Cycloheximide (CHI) inhibits plastid replication completely, but chloramphenicol (CAP) inhibits only to the same extent as darkness. Neither inhibitor can stop the response to light. Replication of plastids in spores that have been incubated in darkness 48 h and transferred to light is prevented by both CHI and CAP, but only for as long as the inhibitors are present. If CHI or CAP is washed out when the spores and sporelings are returned to darkness, plastid replication commences. The data are used to support the concept that the plastids exist in two phases with regard to replication: a light sensitive phase and a light insensitive phase.

THOMAS F. LUCY'S PLANT COLLECTIONS, DONATED TO THE BUFFALO SOCIETY OF NATURAL SCIENCES IN THE EARLY 20TH CENTURY

The botanical collection of Thomas Francis Lucy (1844–1906), which includes voucher specimens for The Flora of the Upper Susquehanna and its Tributaries (Clute 1898), was rediscovered at Elmira College, Elmira, New York in 1984 (Kelloff et al. 1990). These specimens were originally part of the ‘‘Elmira Academy of Sciences, The Upper Susquehanna Flora’’ herbarium, as identified by Lucy’s herbarium labels, and they were transferred to Elmira College around 1881 (Kelloff et al. 1990). This rediscovered herbarium formed the basis for the Elmira College Herbarium (ECH), established in 1985 (Holmgren et al. 1990). Lucy’s Upper Susquehanna flora specimens at ECH-Lucy were believed to be the key to another set of his specimens donated to the herbarium of the Buffalo Society of Natural Sciences (BUF), Buffalo, New York following Lucy’s death in 1906. Much of the history of the Lucy collection has been documented by Kelloff et al. (1990) and Kelloff and Kass (1993). Since Lucy’s field notebooks and catalogue did not accompany the collection that BUF acquired in the early 1920s, the BUF curators had no way to identify the species of most of the unmounted specimens, which were coded only with numbers written on the newspapers that contained them (Kelloff and Kass 1993). Learning that ECH had Lucy’s fully identified and labeled original collection, RHODORA, Vol. 110, No. 944, pp. 484–491, 2008 E Copyright 2008 by the New England Botanical Club