^34 
PHANEROGA MS. 
The Embryo generally attains but very small dimensions in the small-seeded 
parasites and saprophytes destitute of chlorophyll, and remains without differentiation 
until the time of ripening of the seed ; in Monotropa it never consists of more than 
two cells, and even in Pyrola secunda, which possesses chlorophyll, only of from eight 
to sixteen (Hofmeister). The ripe seeds of Orobanche, Balanophora, Rafflesiacese, 
&c. contain a very small undifferentiated embryo in the form of a roundish mass of 
tissue ; the embryo of Cuscula is of moderate size and length, but the formation of 
leaves and roots on the filiform stem ^ is suppressed. The Mistletoe (Loranthaceae), 
on the other hand, parasitic but containing chlorophyll, produces an embryo which 
is not only large but well-developed. 
If the embryo of the ripe seed is differentiated, as is generally the case, it 
consists of an axis and two opposite primary leaves (cotyledons) between which the 
axis terminates as a naked vegetative cone {Cucurbita)^ or bears a bud which some- 
times consists of several leaves {Vicia Faba^ Fig. 436, Phaseolus, Quercus, &c.). 
Instead of the two opposite cotyledons, a whorl of three is not unfrequently formed 
in those plants which normally possess only two ^ [Phaseolus, Aviygdalus, Quercus, 
&c.). The opposite cotyledons are usually alike in form and vigour ; in Trapa 
however one remains much smaller than the other ; and cases even occur in which 
FtG. i,^i,.~Chiijtonantkns fragrans: A horizontal section of the nearly ripe fruit ; B longitudinal section of the 
same, /"the thin pericarp, e remains of the endosperm, «: cotyledons ; C the embryo removed from the seed, showing 
the cotyledons rolled round one another, the radicular end below. 
only one has been formed, as in Ranunculus Ficaria ^, where it remains below in 
the form of a sheath, and in Bulbocapnos, a section of Corydalis'^. The two coty- 
ledons generally form by far the larger part of the ripe embryo, so that the axis 
has the appearance only of a small fusiform appendage between them ; and this 
structure is especially striking when the embryo attains a very considerable absolute 
size in those seeds which possess no endosperm, and the cotyledons swell up into 
two thick fleshy bodies (as in ^sculus, Castanea, Quercus, Fig. 438, Amygdalus, 
Vicia Faba, Phaseolus, the Brazil-nut, &c.) ; but more often the cotyledons remain 
thin like shortly stalked foliage-leaves of simple form (as in Cruciferse, Euphor- 
biacese, and Tilia, the last with a three- to five-lobed lamina). Most often they 
^ According to Uloth (Flora, i860, p. 265) the root-cap is also absent. On parasites see 
especially Solms-Laubach in Jahrb. für wissensch. Bot. vol. VI. pp. 599 et seq. [Uloth's statement is 
confirmed by Koch (Ueb. die Entwick. der Cuscuteen, Hanstein's Bot. Abhdl. II. 1874).] 
^ Numerous additional instances are given in the Bot. Zeitg. 1869, p. 875. [Masters, Vegetable 
Teratology, Ray Soc. 1869, p. 370.] 
^ Irmisch, Beiträge zur vergleichenden Morphologie der Pflanzen, Halle 1854, p. 12. 
* [To these instances of what is termed a ' pseudo-monocotyledonous' development may be 
added Carum Bulbocaslanum (see Hegelmaier, Entwick. dicot. Keime, 1878).] 
