A novel adaptation facilitates seed establishment under marine turbulent flows

Seeds of Australian species of the seagrass genus Posidonia are covered by a membranous wing that we hypothesize plays a fundamental role in seed establishment in sandy, wave swept marine environments. Dimensions of the seed and membrane were quantified under electron microscopy and micro-CT scans, and used to model rotational, drag and lift forces. Seeds maintain contact with the seabed in the presence of strong turbulence: the larger the wing, the more stable the seed. Wing surface area increases from P. sinuosa < P. australis < P.coriacea correlating with their ability to establish in increasingly energetic environments. This unique seed trait in a marine angiosperm corresponds to adaptive pressures imposed on seagrass species along 7,500 km of Australia’s coastline, from open, high energy coasts to calmer environments in bays and estuaries.

A new species of Reissantia (Celastraceae) from coastal Karnataka, India

Reissantia N. Hallé (1958: 466) is a small but widespread genus distributed in the Old World tropics of Africa and Indo-Malaya (Ramamurthy and Naithani, 2000). Members of Reissantia are climbing, scandent or erect shrubs with decussate leaves. They are characterised by small flowers borne in dichotomous cymes or panicles with accessory branches, small calyx and corolla with imbricate aestivation, inconspicuous disc that is mostly fused with the ovary, 3 stamens inserted at the base of the carpel, 3-locular ovary and 3-fascicled capsular fruit with seeds that have a basal membranous wing.

Old World Gesneriaceae: VI. Six miscellaneous notes

I. Lenbrassia G.W. Gillett, which has a zygomorphic corolla and four didynamous stamens with anthers joined, is reduced to Fieldia A. Cunn., which has an actinomorphic corolla and four equal stamens with anthers free; the new combination, F. australiana, is made. II. Boea wallichii R.Br. is distinguished from B. hygrometrica (Bunge) R.Br. with which it has been confused. III. Cyrtandra oblongifolia sensu Kraenzlin is described as a new species, C. kalimantana, allied to C. oblongifolia (Blume) C.B.C1. but distinguished by its hairy leaves, fruits, calyx and corolla; the sterile specimens from Borneo quoted under Cyrtandra rufa Bakh.f. are tentatively referred to C. kalimantana. IV. A specimen of Cyrtandra from the Natuna Islands is identified with C. suffruticosa Ridley from Pulau Tioman and the Malay Peninsula; in contrast two other Gesneriaceae from these islands are of Bornean affinity. V. Didymocarpus pteronema is a new species from Tenasserim province of Burma (= Myanmar): it is anomalous in its campanulate corolla and filaments with unilateral membranous wing. VI. Streptocarpus huamboensis is a new species from Angola allied to S. rhodesianus S. Moore.

The Lodicules of Wheat: Pre- and Post-Anthesis

Development of the lodicules in wheat is described in pre- and post-anthesis flowers. Each lodicule consists of a vascular fleshy body and an avascular membranous wing. At the onset of anthesis, the vascular region swells extensively and subsequently contracts after which the tissues autolyse rap- idly. The membranous wing remains intact. Possible controls and mechanisms of the swelling and destruction of these small organs are discussed.