SA NG U IN A RIA 
573 
apical cell, and the first division of each of these segments divides it 
into a dorsal and a ventral half. In S. the dorsal halves give rise to 
the floating, the ventral to the submerged leaves; in A. the former 
give rise to the leaves, the latter to the branches and roots. The 
sporangia are grouped into sori ; the sorus is enclosed in a highly de- 
veloped indusium, forming a sporocarp. Each sorus contains only one 
kind of sporangium (micro- or mega-sporangia). The sporocarp is an 
outgrowth of a leaf, — in S. of a submerged leaf, in A. of the ventral 
lobe of an ordinary leaf. The spore is covered with an epispore , con- 
sisting of hardened frothy mucilage. It sinks, when set free from the 
sporangium. On germination the microspore forms a rudimentary <? 
prothallus consisting of one (? more) vegetative cell and an antheridium. 
The megaspore forms a $ prothallus, which remains enclosed in the 
burst spore. This prothallus has two parts, an upper small-celled 
green part on which are borne the archegonia, and a lower colourless 
part (of one or more large cells), in which reserves are stored up for 
the use of the young plant which will be formed from a fertilised ovum 
(compare Selaginella and Phanerogams). 
Sambucus (Tourn.) Linn. Caprifoliaceae (i). 20 sp. N. temp., S. Am., 
As. to Austr. S. nigra L. is the common elder. S. Ebulus L. is 
also found in Brit. The genus differs from the rest of the order in 
having compound leaves and extrorse anthers. It also possesses well- 
marked stipules. There has of late been some discussion about the 
proper position to be assigned to it. Fritsch (Nat. PJl .) assigns it a 
separate sub-order. Later he proposed (Bot. Cent. 50, 1892, p. 137, 
168) to fuse Caprifoliaceae with Rubiaceae, but to add S. itself to 
Valerianaceae. Hock (Bot. Cent. 50, 1892, p. 233) thinks this hardly 
justifiable and proposes to erect a new family, Sambucaceae , forming a 
link between the cohorts Rubiales and Aggregatae. He gives a scheme 
showing probable relationships of these orders to the other Sympetalae 
with inferior ovary, and to Umbelliferae &c. A wine is prepared 
from elder berries. 
Samolus (Tourn.) Linn. Primulaceae (11). 8 sp. ; S. Valerandi L., the 
brook-weed, is cosmop., the rest S. Plemisph. The whole plant dies 
down in autumn, but young shoots form in summer and take root, so 
that the parent plant is replaced. The bracts of the firs, are ‘adnate’ 
to the axes, so as to look like solitary bracteoles; this is due to a 
process of growth carrying both bract and axis up together (see p. 30 
and cf. Solanaceae). 
Samyda Linn. Flacourtiaceae. 4 sp. W. Ind. , Mexico. 
Samydaceae (Benth. -Hooker). An order in cohort Passiflorales, com- 
prising the genera Samyda, Casearia. &c. ; placed in Flacourtiaceae by 
Engler. 
Sanguinaria Dill, ex Linn. Papaveraceae (11). 1 sp. Atlantic N. Am., 
S. canadensis L., the blood-root. It has a thick rhizome giving oft’ an- 
nually one leaf and a 1 -flowered scape. The rhizome is used in medicine. 
