Stipules in the Stellatae , with special reference to Galium. 203 
are ‘ leaves ’ at a node. Thus, as many as five stipular primordia may 
occur on either side of a node. 
In this connexion mention may be made of some interesting features 
exhibited by Didymaea mexicana , Hook, fil., 1 which also belongs to the 
Stellatae. As a unique character 2 of this (monotypic) genus the plant has 
been described as having each of its (opposite) leaves provided with a pair 
of typically differentiated stipules, the latter being subulate or lanceolate 
and quite distinct from the true leaves. 3 
In Didymaea there are as a rule four scale-like stipules at a node, 4 but 
very often three stipules are present on one or on both sides of the stem, and 
the middle or additional one is then distinctly smaller than either of the 
other two (Figs. 14, 15). 5 This feature reminds one of the primordial stage 
of the seven- or eight-membered whorls in Aspentla . 6 Although nothing 
is known about the development of the foliar organs in Didymaea , it 
1 In Benth. et Hook., Genera Plantarum, vol. ii (1873), p. 150 ; Hooker’s leones Plantarum, 
vol. xiii (1878), p. 55, tab. 1271. 
2 That is, unique among the Stellatae. 
3 K. Schumann gives in Engler and Prantl’s Pflanzenfamilien, vol. iv (1891), pt. 4, p. 3, 
Rubia diphylla , K. Schum., as another example of a member of the Stellatae having ordinary 
triangular stipules. Neither the figure he refers to nor a description of this plant has ever been given. 
There is, however, little room for doubt that this name (nom. nud.) is a synonym of Relbunium 
diphyllum, K. Schum. (apud Martium, Flora Brasil., vol. vi, pt. 6, 1888, p. 1 1 7 ; also see under 
this genus in the Pflanzenfamilien, vol. iv. p. 154). This plant possesses a minute triangular 
interfoliar stipule on either side of the node, just as in Rubia ephedroides , Cham, et Schltdl. 
(Linneae, vol. iii, 1828, p. 231 ; also see Martius, FI. Brasil., vol. vi, pt. 6, p. 120, Tab. xciii, 
Fig. 1), and R. equisetoides , Cham, et Schltdl. (1. c., p. 231; Martius, 1. c., p. 119). These 
three plants are, however, apparently xerophytes and have their foliar organs very much reduced ; 
the true leaves being scale-like, three or four mm. in length, and only a little larger than 
the stipules, which are similar in shape. It is possible that if the true leaves could be induced 
to develop to a respectable size, the stipules would also become much larger, assuming exactly the 
same shape as the former. It is therefore obvious that these three species are not suitable as examples 
of the exceptional phenomenon among the Stellatae of scale-like stipules alternating with the true 
leaves, which are decussate and of normal appearance. So far as the writer knows, Galium para- 
doxum , Maxim., G. geminifolium , F. von Muller, Asperula geminifolia, F. von Muller, and Didymaea 
mexicana , Hook, f., are the only members of the Stellatae showing this rare phenomenon, and of 
these the first-named plant produces scale-like stipules at the lower nodes only, those at the middle 
and upper nodes of the stem being leaf-like. Both Galium geminifolium and Asperula geminifolia 
are Australian plants (cf. Bentham, Flora Australiensis, vol. iii, 1866, pp. 445 and 443), and usually 
bear at each node two opposite, narrow leaves, and two small scale-like stipules alternating with the 
former (cf. K. Schumann, in Engler and Prantl, Pflanzenfamilien, vol. iv, pt. 4, p. 15 1, Fig. 48 d). 
In G. geminifolium , however, the stipules are occasionally well developed, either becoming leaf-like 
or showing a transition. This is probably due to a change in some physiological conditions (such 
as might l}e caused by rain, &c.) at the time when the foliar organs are developing. 
It may be remarked here that Velenovsky (1. c., p. 434) gives Putoria as an example of the 
genera whjch belong to the Stellatae and bear interpetiolar stipules alternating with two opposite 
leaves. However, all the leading systematists agree to refer this genus to the tribe Anthospermeae ! 
4 Cf. K. Schumann, in Engler and Prantl, Pflanzenfamilien, vol. iv, pt. 4, p. 147, Fig. 47, N, o. 
5 Only once has the writer met with four stipules on one side of a node ; this was in one of the 
specimens distributed under Pringle, Plantae mexicanae, No. 4716 (1894). In this case also, the 
two middle ones are smaller than the other two stipules. 
6 Cf. Franke, 1. c., p. 51, Taf. i, Fig. 8. 
