Briggs and Johnson, Hopkinsiaceae and Lyginiaceae 
491 
various Restionaceae and sclerenchyma girders are all absent. (Cutler [1969 Fig 351 
identifies thick-walled cells in the chlorenchyma of Lyginia as pillar cells, but notes [p 
234] that They are derived from palisade chlorenchyma cells [rather than cells of the 
parenchyma sheath] and therefore cannot be regarded as true pillar cells.') To the 
inside of the chlorenchyma is the parenchyma sheath, l(-2) cells thick surrounding the 
sclerenchyma cylinder. The outer vascular bundles are embedded in the sclerenchyma 
cylinder, the inner bundles are scattered in the pith. Some pith cells include slab¬ 
shaped crystals; there is no central cavity. The central ground tissue is 
sclerenchymatous around the lignified bundle sheaths, and there are numerous 
intercellular spaces. The anatomy of rhizomes and roots is illustrated by Meney, Pate 
and Hickman (1999) and further description of morphology and anatomy given by 
Pate and Meney (1999) and Pate and Delfs (1999). 
Lyginia shows several distinctive anatomical features (Gilg 1891; Cutler 1969): the thin- 
walled cells lining the substomatal cavity which are unlike those of genera in related 
families that show differentiated substomatal cells, the oblique epidermal cells, 
stomata at an angle to the epidermal cells, and slab-shaped crystals in some cells of the 
central ground tissue. The absence of silica also contrasts with the usual condition in 
Restionaceae. Cheadle (1955) considered the vessels of the shoot system (but not of the 
roots) of Lyginia to show especially primitive characteristics. 
Inflorescence and flower structure: inflorescences are blastotelic (not terminated by a 
flower [Briggs & Johnson 1979]) and anauxotelic (axes not growing on after flowering); 
with rigid, acuminate culm spathes at 1-several uppermost culm nodes, subtending 
short flowering branches that may bear smaller spathes subtending very short 
flowering branches; each flower subtended by a glume-like bract. Female 
inflorescences are fewer-flowered and less branched than the males. Male and female 
flowers are described above for the family. 
Pollen morphology and embryology: the single pollen grains are spheroidal to oblate, 
c. 30-38 pm polar diameter (Chanda 1966; Ladd 1977). The pollen walls show a foot- 
layer, columellate interstitium, and a thin tectum, with numerous pores penetrating 
the tectum and the foot-layer ('scrobiculi'), as well as pores ('puncta') that penetrate 
the tectum only. The pollen surface has micro-verrucate ornamentation. The annulus 
consists of a heavily thickened foot-layer, and the aperture is of 'graminoid' type 
(Linder & Ferguson 1985) with a diameter about 7 pm. A thin layer of endexine covers 
the ulcus and extends some distance under tine margins. The endothecium of the 
anthers contains spiral thickenings but these often form U-shapes rather than 
complete helices, showing similarity to the condition in Anarthriaceae (Manning & 
Linder 1990). The ovary walls are impregnated with tannins. Linder (1992) observed 
that the ovary is similar to that of Anarthria but has small densely packed cortical cells 
more like those of Hopkinsia. The orthotropous, tenuinucellate ovules are bitegmic, 
with the inner integument tanniniferous. Megagametophyte development is not 
known beyond the 8-nucleate stage but there are three antipodals and large starch 
grains in the mature megagametophyte (Rudali & Linder 1988). The development of 
the embryo has not been studied. 
Karyology: Lyginiaceae have the number of n = 6 (Johnson & Briggs 1981; Bell & Pate 
1993) which is not known in the Restionaceae and the chromosomes are larger than in 
the latter family, although not as large as in Anarthriaceae (Briggs 1966). [Johnson and 
Briggs (1981) corrected a previous erroneous count by Briggs (1966)]. Bell and Pate 
studied all species and observed that there 'were no apparent differences in size or 
configuration of chromosomes among [them]'. 
Fruit and seed: the capsule develops from a 3-locular ovary, with one seed per locule. 
The seed has a readily detached, white outer layer. The surface is highly distinctive 
