a 
There is, however, no such sweeping sharp demarcation be- 
tween families in reference to their temperature tolerations as 
might be expected from a general acquaintance with their com- 
monly known herbaceous perennial and woody plant members. 
Some families predominantly tropical have many temperate * 
representatives. Such is the case with the Araceae, Orchidaceae, 
Papilionaceae, Euphorbiaceae, Solanaceae, and Oxalidaceae. Other 
tropical families having few temperate herbaceous perennial 
woody representatives are Bignoniaceae, Meliaceae, Sapotaceae, 
Passifloraceae, Anonaceae, Rubiaceae, Verbenaceae, Symplocaceae, 
and Aristolochiaceae. 
No attempt is made in the present publication to do more than 
cite examples, as I expect to treat this whole subject in great 
detail in a later paper. 
Evidence based on plant families however is not as convincing 
as that drawn from the distribution of species within a genus, or 
from the geographical distribution of certain single species, since 
many botanists are inclined to be skeptical of families as natural 
groups, from a genealogical standpoint. There is less skepticism 
as to the genealogical relationships of species within a genus 
and individuals within a species. 
The genera predominantly tropical or sub-tropical with herba- 
ceous perennials or woody representatives at the Arnold Ar- 
boretum, and listed as hardy there by Sargent ft (1922), are 
Leitneria, Aristolochia, Desmodium, Indigofera, Sophora, Erodta, 
Picrasma, Cedrela, Andrachne, Sapindus, Meliosma, Zizyphus, 
Grewia, Hibiscus, Bumelia, Diospyros, Styrax, Symplocos, Jas- 
minum, Marsdenia, Callicarpa, Clerodendron, Vitex, Solanum, 
Bignonia, and Asimina. 
Several other genera, common in the tropics, with cool-tem- 
perate representatives that are herbaceous perennials or woody 
plants are Lygodium, Trichomanes, Adiantum, Pteridium, Selagi- 
nella, Equisetum, Salix, Ficus, Sapium, Oxalis, Tillandsia, Puya, 
- Aalanthus, Tessaria, Passiflora, Tripsacum, and Gordonia. 
The genus Citrus should also be included here through its 
recently segregated form Poncirus trifoliata, which is hardy in 
* Temperate here means cool temperature where zero (Fahrenheit) tem- 
perature may be expected. ‘Tropical refers to frost-free regions. 
t Only some of the more striking are listed here. 
