POLLEN. 



[ 618 ] 



POLLEN. 



d. Outer coat with irregular reticulations : 

 Alstrameria C'urtisiana. 



Among tlie Orchidese are found quater- 

 nate grains belonging to this group. 



** Outer coat with two furrows : a rare 

 form, occurring iu species of Fonte- 

 deria and Amaryllis, Tamits commu- 

 nis and elephaniipes, Tigridia paw- 

 nia, Calycanthus JluriduSj &i'c, 



*** Outer coat with three longitudinal 

 furrows. 



a. Outer coat granular. One of the com- 

 monest forms : Quercus Rohur, Viola 

 odorata (PI. 40. tig. 6). 



h. Outer coat with short spines : Cactus 

 Jiayelliformis, Viscum cdbum. 



c. Outer coat with cell-like reticulations : 

 Statice (PI. 40. fig. 29), various Cruci- 

 ferse. 



**** Outer coat with more than three 

 furrows. 



a. Four : very rare as normal, Hoiisfonia 

 cccrulea, Cedrela odorata; occasionally 

 occurring where three is the normal 

 niimber, as in Solamnn tuberosum. 



b. Six : some of the Labiata? and Passi- 

 florefe (PI. 40. fig. 20), Ephedra dista- 

 chya, Heliotropium grandlflorum. 



c. A large number of furrows : many 

 Ptubiacefe, e. g. Sherardia arvensis (PI. 

 40. fig. 18). 



The pollen of the Pines is related to this 

 group, also that of Nymphd'a Lotus, Victo- 

 ria reyia, and other plants, where the fur- 

 rows or thin places occupy the greater part 

 of the wall, and the outer coat forms only 

 segmental pieces. In Thunbcryia alata 

 (PI. 40. fig. 24 a) a remarkable appearance 

 arises from the furrows running in a curved 

 or spiral direction. 



C. Outer coat with pores. 



* A single pore : Grasses, Sedges, Ttj- 

 pha anyustifolia, Sparyanium ra- 

 mosum. 



** Two pores : Colchicum, and a few 

 other Monocotyledons^ also JJrous- 

 sonetia. 



*** Three pores. 



a. Outer coat granular : Dipsacero, Urti- 

 caceaj, Onagraceae [here the pores form 

 projecting processes (PI. 40. fig. 14) ; 



and in Mori?ida pet'sica this is still more 

 the case] ; Cucimm satirus. 



b. Outer coat with cell-like reticulations : 

 many Passiflorere — with large lids, P. 

 cccrulea (PI. 40. fig. 13), alata, ^-c. 



**** Four pores. 



a. Pores on the equator : Pistacia tere- 

 binthus, Campanula rotundifolia, ^c. 



b. Pores not equatorial : Passijlora ker- 

 mesina, Impatiens Balsamina (PI. 40. 



fig. 21) {Noli-me-tanyere). 



***** More than four pores. 

 t Distributed regvilarly. 



a. On the equator : Alnus ylufinosa, Ul- 

 mits camjyestris, Collomia linearis, Cam- 

 2>amda Specidum. 



b. All over the gi'ains : Basella alba (PI. 

 40. fig. 19). 



tt Scattered irregularly. 



a. Outer coat shghtly granular : many 

 Nyctaginepe, Convolvulaceas, Chenopo- 

 diacese, Alsineae, Alisma Plantayo ( PI. 

 40. fig. 10), Plantayo lanccolata, liibes 

 yjiyrum, Cactus Opuntia, Sfc. 



b. Outer coat granular and spinv : Cvcur- 

 bita Pepo (with lids, PI. 40'. fig. 22), 

 Malvaceaj (fig. 26). 



c. Outer coat with cell-like reticulations : 

 Polyyonum amiiliibium, pcrsicaria, Co- 

 bcea scandens. 



Compound porous forms occur in some 

 of the Onagraceai, and in Drimys Winteri, 

 where four grains are conjoined telralie- 

 drally. In the MimosejB groups of eight 

 or sixteen (PI. 40. fig, 25) occur in A-arious 

 forms. In Zesc/ienaultiafor7nosa the grains 

 are quaternate, lying in one plane. 



D. Outer coat with both furrows and pores. 



* Grains rounded or depressed, with 

 three depressions, each with a pore : 

 most l)ipsacea3 and Geraniacese 

 (sometimes only two occur, PI. 40. 

 fig. 22). 



** Three furrows and three pores. 



a.. Outer coat granular : a very common 

 form among Dicotyledons. 



b. Outer coat spiny : most Compositoe. 



0. Outer coat with cell-like reticulations ; 

 rare : Syrinya vulyaris, Liyustrum lul- 

 gare, Greioia occidcntalis, and other 

 species. 



