6. PANDANACEAE — 7. SPARGANIACEAE — 8. POTAMOGETONACEAE 73 



FAMILY 6. PANDANACEAE 



Shrubs or trees, usually with aerial roots. Leaves in tliree ranks, sword- 

 shaped, usually spiny. Flowers dioecious, without bracts, arranged in sohtary 

 or panicled, spike- or head-like spadices, which are inserted in the axil of spathe- 

 like bracts. Perianth none. Ovaries connate, i-celled. Ovule i, descending, 

 inverted. Stigma i, sessile. Fruits drupe-hke, congested into a globose or 

 ovoid head. Seed with abundant albmnen. (Plate 3.) 



Genus i, species 65. Tropics. They yield timber, fibres, flowers used in 

 perfumery, edible fruits, and medicinal drugs. " Screw-pine." 



Pandanus L. 

 FAMILY 7. SPARGANIACEAE 



Aquatic or marsh herbs with a creeping root -stock. Leaves in two ranks, 

 linear. Flowers unisexual, in globular heads, the lower of which are female. 

 Perianth of membranous scales. Stamens 3 or more. Ovary superior, 1—2- 

 celled. Ovule i in each cell, pendulous, inverted. Style simple , stigmas 

 1—2. Fruits drupe-like. Seed with a mealy albumen and a large, axile 

 embryo. (Under TYPHACEAE.) 



Genus i, species 2. North-west Africa. " Bur-reed." Sparganium L. 



ORDER HELOBIAE 



SUBORDER POTAMOGETONINEAE 

 FAMILY 8. POTAMOGETONACEAE 



Aquatic herbs. Leaves with axillary scales. Flowers sohtary or spicate, 

 regular, with i — 4-merous whorls. Perianth simple and little developed or 

 wanting. Stamens i — 4. Anthers sessile, opening outwards or laterally. 

 Carpel i, with a i-celled ovary, or several distinct or almost distinct carpels. 

 Ovules solitary in each carpel, very rarely 2, pendulous or laterally fixed 

 Fruit indehiscent. Seed exalbuminous. Embryo with a strongly developed 

 radicle. — Genera 8, species 35. (Including ZOSTERACEAE, under 

 NA I ADA CEA E.) (Plate 4.) 



1. Flowers in spikes, hermaphrodite or polygamous, without a perianth, 



but the stamens sometimes provided with a sepal-Hke connective. 2 

 Flowers solitary or in cymes, unisexual 5 



2. Spikes with a flat axis, at the time of flowering enclosed in the sheaths 



of the uppermost leaves. Stamen i. Pollen-grains filiform. Carpel 

 I. Stigmas 2, on a short style. Embryo with a very large radicle and a 

 tail-hke cotyledon. Submerged marine plants. — Species 2. North and 

 South Africa and Madagascar. Used for stuffing and as packing material. 



"Grass-wrack." [Tribe ZOSTEREAE.] Zostera L. 



Spikes with a cyhndrical axis, at the time of flowering not enclosed in the 

 sheaths of the uppermost leaves. Stamens 2—4. Stigma i, undivided 

 or many-parted 3 



